Pest seasons where you live

Also called: greenfly, blackfly, plant lice

What you'll see: Clusters of soft, pear-shaped insects on new shoots and leaf undersides. Look for white shed skins, sticky honeydew, sooty mold, and curled or yellowed leaves. Tan, swollen 'mummies' mean parasitic wasps are at work.

Where it lives: Many species; found on garden and landscape plants across the US. In mild coastal California some are active year-round.

In short: First colonies on new growth: about late Apr to mid May in zone 6 (typical last frost mid Apr), late Mar to mid Apr in zone 8 and mid May to mid Jun in zone 4. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in February, March, April, May, October, November. Indoors: Indoors and in greenhouses they reproduce year-round with many overlapping generations.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Active much of the year in mild coastal climates; populations build fastest in mild spring weather and many species decline in hot inland summers, with winged dispersers more common in spring and fall. In Florida green peach aphid is a listed pest of tomato/pepper; no month-by-month calendar was found. Peak months: February, March, April, May, October, November.

Indoors and in greenhouses

Indoors and in greenhouses they reproduce year-round with many overlapping generations. They commonly ride in on plants returning in fall or on new plants. Kentucky notes sap feeders such as aphids become more common on houseplants in winter.

When it spikes:

• Plants come back indoors: in zone 6, about mid Sep to mid Oct
• Sap feeders build up indoors over winter: while the heat is on, roughly first frost to last frost

Check again in: 7 days. Short development time and high reproduction (UConn). Nymphs mature in 3–4 weeks and generations overlap (Purdue, cannabis aphid). Look for mummies 2–3 weeks after releasing parasitoids.

What research says works

• Convergent lady beetles (adults) (outdoors): Release only once aphids are present; release at dusk after misting plants. Most fly off within days, so expect short-term control and repeat releases on heavy infestations.
• Green lacewing larvae, syrphid fly larvae, soldier beetles (outdoors): Natural enemies build after aphids become numerous; conserve them by avoiding broad-spectrum insecticides, controlling ants, and planting nectar/pollen flowers.
• Aphid parasitoid wasps (e.g., Aphidius-type) (outdoors): Look for mummies before spraying; parasitized colonies are already under control. UC names parasitic wasps generally; genus-level release guidance was not in cited sources.
• Aphidius colemani (indoors): For green peach and melon aphids. Release preventively, in the evening, in shade, at 65–77°F and 70–85% RH. Less effective above 86°F. Remove sticky cards and look for mummies after 2–3 weeks.
• Aphidius ervi / Aphelinus abdominalis (indoors): For larger aphids such as foxglove and potato aphids. Aphelinus tolerates more heat but works more slowly.
• Aphidoletes aphidimyza (predatory midge) (indoors): Best at 60–80°F and 50–85% RH. Larvae need at least 15.5 h of light or they enter diapause, which happens from about September to March. Low-intensity light extension prevents it.
• Green lacewing larvae, lady beetles (indoors): Expect reduction in about 2 weeks with lacewings, which leave above 95°F.

From FGMN

• Aphidius colemani
  The aphid specialist for small aphids; start here
• Aphidius ervi
  For the larger aphids
• Aphidoletes aphidimyza
  Fast knockdown of heavy colonies (needs long days)
• Green Lacewing Larvae
  Hungry general aphid predator
• Ladybugs
  Outdoors once aphids are present; release at dusk
• Green Lacewing EggsPrevention only
  Prevention, before aphids show up

Read our full aphids guide

Timing: one good source

Sources (10)

1. Frost/Freeze climatology (Louisville, Lexington, Bowling Green, Frankfort), NOAA National Weather Service, Louisville KY
2. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
3. Pest Notes: Aphids, UC Statewide IPM Program
4. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension
5. How and when do I bring my houseplants back indoors before winter?, Iowa State University Extension and Outreach
6. Moving Indoor Plants Outside for the Summer, Iowa State University Extension and Outreach
7. Bringing houseplants back inside, University of Minnesota Extension
8. Keeping Your Houseplants Happy During Wintertime, University of Kentucky Cooperative Extension, Carter County
9. Biological Control of Aphids, UConn Extension IPM
10. Management Strategies for Common Arthropod Pests of Greenhouse Hemp in Indiana (E-275), Purdue Extension

Also called: spider mites, red spider mite, two spotted mites, TSSM

What you'll see: Fine pale stippling on leaves that turn dull and yellow or bronzed, then fine webbing on tips and between leaves. Tiny mites and eggs sit on leaf undersides along the veins. Tap a leaf over white paper and look with a 10x lens.

Where it lives: Warm-season mite on vegetables, flowers, shrubs and fruit across the US; worst in hot, dry, dusty conditions and on water-stressed plants.

In short: Peak outdoor outbreaks in hot, dry weather: about late Jul to late Aug in zone 6 (typical last frost mid Apr), late Jun to late Jul in zone 8 and mid Aug to mid Sep in zone 4. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in May, June, July, August, September. Indoors: Year-round indoors, with a jump in winter in heated homes.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Overwintering females resume feeding with spring warmth; populations explode in hot dry periods and often crash in late summer as predators build or rain/cooler weather arrives. In Florida tomatoes, problems concentrate at the end of the season under hot, dry conditions. Peak months: May, June, July, August, September.

Indoors and in greenhouses

Year-round indoors, with a jump in winter in heated homes. Furnace heat can drop indoor humidity to 10–20%, and spider mites love warm, dry air. Plants coming back inside after summer can also bring mites in. In greenhouses they are most explosive in hot summer conditions (above 80°F, 20–40% RH) and often start near heat sources.

When it spikes:

• Heating dries the winter air: while the heat is on, roughly first frost to last frost
• Plants come back indoors: in zone 6, about mid Sep to mid Oct

Check again in: 5-7 when warm; 14-20 when cool days. Egg to adult takes as few as 7 days at 81°F but about 20 days at 64°F (UMass). Purdue gives 5–10 days per generation under optimal conditions. UMass advises weekly scouting.

What research says works

• Phytoseiulus persimilis (predatory mite) (outdoors): Release as soon as mites are first seen, concentrated on hot spots. Works best above ~68°F with humidity above ~75%; struggles above ~86°F or below 60% RH.
• Neoseiulus californicus (predatory mite) (outdoors): Preventive or low-population releases; tolerates 46–95°F and 40–80% RH, so better than persimilis in fluctuating outdoor conditions. Can be combined with persimilis.
• Western predatory mite (Galendromus occidentalis) (outdoors): Suited to hot, dry conditions (50–115°F, 30–60% RH). Aim for roughly 1 predator per 10 spider mites; knock down heavy infestations with soap first.
• Phytoseiulus persimilis (indoors): A spider-mite specialist. Best at about 68°F and 75% RH or higher. Below 60% RH its eggs shrivel and fail to hatch, and above about 86°F spider mites outpace it. Release early, when mites are first seen. Colonies should decline in 2–3 weeks, and a second release a week later may be needed.
• Neoseiulus californicus (indoors): Tolerates hotter and drier conditions than persimilis: about 46–95°F and 40–80% RH. Can be released preventively at low mite numbers and survives on other food, which suits fluctuating conditions and dry indoor air.
• Amblyseius andersoni (indoors): Active from about 42°F to 104°F and tolerates cool conditions better than other predatory mites. Release when mite numbers are low.
• Feltiella acarisuga (predatory midge) (indoors): Best at 68–80°F and about 80% RH. Survival drops if RH stays below 60%.

From FGMN

• Phytoseiulus persimilis
  The specialist, for humid rooms and mild weather
• Neoseiulus californicus
  For hot or dry rooms and outdoor swings
• Spider Mite Rapid Response
  Both of the above together
• Neoseiulus californicus Slow-Release Prevention SachetsPrevention only
  Prevention in hot or dry spots
• Phytoseiulus persimilis Slow-Release Prevention SachetsPrevention only
  Prevention in humid spots

Read our full two-spotted spider mites guide

Timing: one good source

Sources (12)

1. Frost/Freeze climatology (Louisville, Lexington, Bowling Green, Frankfort), NOAA National Weather Service, Louisville KY
2. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
3. Pest Notes: Spider Mites, UC Statewide IPM Program
4. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension
5. Biological Control of Spider Mites (greenhouse fact sheet), UConn Extension IPM
6. How and when do I bring my houseplants back indoors before winter?, Iowa State University Extension and Outreach
7. Moving Indoor Plants Outside for the Summer, Iowa State University Extension and Outreach
8. Keeping Your Houseplants Happy During Wintertime, University of Kentucky Cooperative Extension, Carter County
9. Twospotted Spider Mites, UMass Amherst Greenhouse Crops & Floriculture
10. Biological Control of Spider Mites, UConn Extension IPM
11. Phytoseiulus persimilis (Biological Control: A Guide to Natural Enemies), Cornell University
12. Management Strategies for Common Arthropod Pests of Greenhouse Hemp in Indiana (E-275), Purdue Extension

Also called: thrip, western flower thrips, WFT

What you'll see: Silvery flecks or streaks on leaves with tiny black fecal dots. Flowers and new shoots are deformed or streaked, and white streaks appear on petals. To find the slender 1–2 mm insects, tap blooms over white paper. Blue sticky cards catch more thrips than yellow ones. Thrips can spread tospoviruses (INSV/TSWV), which cause ringspots and necrotic spots.

Where it lives: Found statewide in Florida and common in California gardens; it moves into gardens when nearby weeds and grasslands dry out. A national range map was not in cited sources.

In short: Indoors: Year-round wherever plants are kept warm.

Warm-winter areas (zones 9–11): Up to ~8 generations a year; egg to adult in about 2 weeks in warm weather. Vectors tomato spotted wilt virus. No month-level calendar found.

No dated outdoor timing found in extension sources reviewed; stages left empty rather than invented.

Indoors and in greenhouses

Year-round wherever plants are kept warm. In greenhouses, a big influx comes in summer when outdoor weeds dry down or are mowed and adult thrips fly in looking for new hosts. Thrips also arrive on new plants and cuttings in any season. They do not develop below about 50°F.

When it spikes:

• Thrips fly in when outdoor weeds dry out or get mowed: in zone 6, about early Jun to mid Aug
• New plants, plugs or cuttings brought in: any time of year

Check again in: 7 days. One generation takes about 7–14 days at fluctuating 68–98°F. UConn recommends weekly sticky-card counts.

What research says works

• Minute pirate bugs, green lacewings, predatory mites (conservation) (outdoors): UC says there is little research-based information on releasing thrips enemies in gardens and that purchased releases are unlikely to give satisfactory control outdoors; conserve resident predators instead.
• Neoseiulus (Amblyseius) cucumeris (indoors): Release preventively before thrips are seen, because it attacks only first-instar larvae. Slow-release sachets last 4–6 weeks. Best at 75–85°F with RH above 65%. More economical in winter, short-day conditions. Keep sachets shaded.
• Amblyseius swirskii (indoors): Suggested for warm summers (70–80°F, about 70% RH). It outperformed cucumeris under hot, bright, long-day conditions but costs more. Not suited to tomatoes.
• Orius insidiosus (minute pirate bug) (indoors): Most effective at 68–85°F. Needs pollen. Can take 8–10 weeks to establish, so it suits long-term crops. Females enter reproductive diapause under short days (critical photoperiod about 12–13 h of light), which makes it less reliable in winter without long days.
• Stratiolaelaps scimitus and Dalotia coriaria (indoors): Soil-dwelling predators that eat thrips pupae in the media. Used as a supplement to cucumeris.
• Steinernema feltiae (indoors): A media drench followed by weekly sprays. Apply early or late in the day and protect from UV and heat.

From FGMN

• Amblyseius swirskii
  Thrips on leaves in a humid room
• Neoseiulus cucumeris
  Thrips on leaves in a dry or cooler room
• Thrips Rapid Response - Two Stage System
  Leaves and soil at once (swirskii + Sf nematodes)
• Amblydromalus limonicus
  The strongest single thrips predator
• Sf Nematodes
  The stage that drops to the soil
• Amblyseius swirskii Slow-Release Prevention SachetsPrevention only
  Prevention only, before you see thrips

Outdoors in gardens, research says bought thrips predators rarely pay off; these picks are for indoor plants and greenhouses.

Read our full thrips guide

Timing: rough estimate

Sources (6)

1. Pest Notes: Thrips, UC Statewide IPM Program
2. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension
3. Managing Western Flower Thrips on Greenhouse Crops, UConn Extension IPM
4. Biological Control of Western Flower Thrips, UConn Extension IPM
5. Thrips Management in Greenhouses (FS-762), University of Maryland Extension
6. Seasonal Distribution and Overwintering of Orius insidiosus (Say) in Arkansas (Elkassabany, Ruberson & Kring 1996, J. Entomol. Sci. 31:76-88), Journal of Entomological Science (peer-reviewed)

Also called: white flies, greenhouse whitefly

What you'll see: Clouds of tiny white flies, wings held flat, burst up when the plant is touched. Scale-like nymphs sit on leaf undersides. Leaves yellow and get sticky with honeydew and sooty mold. Pupae are white with waxy filaments.

Where it lives: Silverleaf/sweetpotato and greenhouse whiteflies breed year-round outdoors in warm regions (southern California desert, southern Texas, south/central Florida). In colder areas outdoor problems usually start from infested transplants. States: CA, AZ, TX, FL.

In short: In frost-free areas (zones 10–11) it peaks in August, September, October. Indoors: Cannot overwinter outdoors in cold northern states like Massachusetts, so it survives in greenhouses and homes.

Warm-winter areas (zones 9–11): California cucurbits: numbers peak in late summer and decline by November. Florida: highest in south, southwest and west-central areas; in west-central Florida virus-carrying whiteflies are usually more numerous in fall; north Florida sees them mainly in spring. Peak months: August, September, October.

No frost-anchored temperate outdoor timing was found; stages left empty. Peak months come from UC's 'late summer, declining by November' and Florida's fall note.

Indoors and in greenhouses

Cannot overwinter outdoors in cold northern states like Massachusetts, so it survives in greenhouses and homes. Adults migrate out as it warms in spring, and in fall adults on outdoor weeds move back into greenhouses. Houseplants returning indoors in fall can also carry whiteflies in. Poinsettias and holiday plants are major hosts.

When it spikes:

• Whiteflies move in from outdoor weeds and returning plants: in zone 6, about early Sep to late Oct
• Plants moved outdoors in spring

Check again in: 7 days. Egg to adult takes 14–40 days depending on temperature (UMass) or 14–28 days (Purdue). UMass replaces sticky cards weekly.

What research says works

• Eretmocerus eremicus / E. mundus (parasitic wasps) (outdoors): Recommended by Texas A&M; release at first detection of nymphs.
• Encarsia formosa (parasitic wasp) (outdoors): Mainly for greenhouses; UC does not generally recommend it outdoors because it survives poorly in temperate climates.
• Delphastus lady beetles, green lacewing larvae, bigeyed bugs (outdoors): Predators of eggs and nymphs; conserve, and keep ants and dust down.
• Encarsia formosa (indoors): Most effective at 70–80°F and 50–80% RH. Adults won't fly below 65°F and survival drops above 86°F. Release weekly until about 80% of nymphs are parasitized. Keep cards out of direct sun.
• Eretmocerus eremicus (indoors): Also attacks greenhouse whitefly. Best at 77–84°F and inactive above 86°F.
• Delphastus catalinae (whitefly-eating lady beetle) (indoors): Eats eggs and small nymphs (Purdue).
• Amblyseius swirskii (indoors): Eats whitefly eggs and nymphs as well as thrips (UMass).

From FGMN

• Amblyseius swirskii
  Eats whitefly eggs and young nymphs
• Amblydromalus limonicus
  Eats whitefly eggs and nymphs; works in cooler rooms too
• Horiver Professional Sticky TrapsMonitoring
  Yellow cards to count adults week to week

Timing: rough estimate

Sources (8)

1. Cucurbits Pest Management Guidelines: Whiteflies, UC Statewide IPM Program
2. Whitefly Management Guide for Horticultural Crops, Texas A&M AgriLife Extension
3. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension
4. Pest Notes: Whiteflies, UC Statewide IPM Program
5. How and when do I bring my houseplants back indoors before winter?, Iowa State University Extension and Outreach
6. Bringing houseplants back inside, University of Minnesota Extension
7. Whiteflies on Greenhouse Crops, UMass Amherst Greenhouse Crops & Floriculture
8. Management Strategies for Common Arthropod Pests of Greenhouse Hemp in Indiana (E-275), Purdue Extension

Also called: mealy bugs, millie bugs, root mealybugs, white fuzz on plants

What you'll see: White, cottony fluff in leaf axils, along midribs, under leaves and at stem bases. Plants are sticky with honeydew and may have black sooty mold or ants. Stunting and yellowing follow. Root mealybugs have no obvious filaments. They show up as white waxy patches on roots when the plant is unpotted, and are worst on potted plants such as African violets.

Where it lives: Outdoor pests mainly in mild-winter areas such as southern and coastal California (citrus, grape, hibiscus, succulents, cactus, gardenia). Other frost-free states are likely but not documented in cited sources. States: CA, FL.

In short: Indoors: Year-round indoors, where all life stages can be present at once.

Warm-winter areas (zones 9–11): Favored by warm weather; 2–6 generations outdoors per year depending on species. On deciduous hosts they overwinter as eggs or young nymphs under bark.

No month-level outdoor calendar found in sources.

Indoors and in greenhouses

Year-round indoors, where all life stages can be present at once. They mostly arrive on new tropical, foliage and succulent plants, or on plants carried over between seasons or brought back in after summer. They build slowly at first, then rapidly.

When it spikes:

• Plants come back indoors: in zone 6, about mid Sep to mid Oct
• New plants purchased: any time of year

Check again in: 7 days. Crawlers keep emerging for up to 45 days. Contact treatments need 2–3 weekly applications because generations overlap, and UC IPM suggests repeating alcohol sprays weekly.

What research says works

• Mealybug destroyer (Cryptolaemus montrouzieri) (outdoors): Release when mealybug egg sacs are abundant, since beetles need eggs to reproduce; pointless at low mealybug numbers. Cold-intolerant, so it persists mainly in southern and coastal California and is re-released after cold winters.
• Parasitic wasps (Leptomastix, Coccophagus, Allotropa, Acerophagus, Pseudaphycus) (outdoors): Check for mummies or exit holes before treating; conserve, and control ants.
• Cryptolaemus montrouzieri (mealybug destroyer) (indoors): Best at 72–77°F and 70–80% RH, and most active on sunny days, less so on short winter days. Release only when mealybugs and their egg sacs are abundant, because the beetle needs egg masses to reproduce. It is not effective on longtailed mealybug, which produces no egg sacs. Control ants first. Release in the evening.
• Green lacewing larvae (Chrysoperla) (indoors): Active at 54–95°F. Repeat releases are often needed.
• Leptomastix dactylopii (parasitoid) (indoors): Attacks only citrus mealybug (UC IPM).

From FGMN

• Cryptolaemus montrouzieri
  The mealybug specialist; release at the colony
• Green Lacewing Larvae
  Backup predator on light infestations

Read our full mealybugs guide

Timing: rough estimate

Sources (6)

1. Pest Notes: Mealybugs, UC Statewide IPM Program
2. How and when do I bring my houseplants back indoors before winter?, Iowa State University Extension and Outreach
3. Bringing houseplants back inside, University of Minnesota Extension
4. Managing Mealybugs in the Greenhouse, UConn Extension IPM
5. Mealybugs (Pest Notes 74174), UC Statewide IPM Program
6. Biological Control of Mealybugs, UConn Extension IPM

Also called: scale insects, brown scale, lecanium scale, magnolia scale

What you'll see: Smooth, rounded tan to brown bumps (up to about 1/4 inch) on stems and leaf veins that look like part of the plant. Plants are sticky with honeydew and may have sooty mold and ants, and leaves yellow. Crawlers are tiny, yellow-orange and mobile. Parasitized scales turn darker and have exit holes. A live scale oozes liquid when crushed.

Where it lives: Many species on trees and shrubs nationwide. Cited timing is from Maryland (oak lecanium) and Massachusetts/Kentucky (magnolia scale).

In short: Oak lecanium crawlers active – best treatment window: about mid Jun to early Jul in zone 6 (typical last frost mid Apr), mid May to early Jun in zone 8 and early Jul to late Jul in zone 4. It moves with your local frost dates. Indoors: Year-round indoors with overlapping generations.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Most soft scales have one generation a year and overwinter as second-instar nymphs; brown soft scale has several generations with all stages present year-round in warm areas.

Indoors and in greenhouses

Year-round indoors with overlapping generations. Indoor scales reach maturity in about 65 days. They often arrive on new plants or ride in on plants returning in fall. Common on ferns, orchids, schefflera, ficus, citrus and ivy.

When it spikes:

• Plants come back indoors: in zone 6, about mid Sep to mid Oct

Check again in: 10 days. Wisconsin suggests 2–3 treatments 10 days apart. Crawlers hatch 1–3 weeks after eggs are laid. Indoor scales reach maturity in about 65 days, and generations overlap (Cornell).

What research says works

• Parasitic wasps (Metaphycus, Coccophagus, Encarsia) (outdoors): Conserve during crawler season. Avoid long-residual and pyrethroid sprays, which UMD links to lecanium outbreaks.
• Scale-feeding lady beetles (Chilocorus, Hyperaspis, Rhyzobius) (outdoors): Larvae feed hidden under scales; commercial releases are documented mainly for certain scales (e.g., California red scale), and results take a season or more.
• Parasitic wasps (Metaphycus, Coccophagus, Encarsia) (indoors): UC IPM names them as natural enemies of scale. No indoor release conditions are sourced. Wisconsin notes few commercial natural enemies exist for greenhouse soft scale.
• Lady beetles (Chilocorus, Rhyzobius lophanthae, Hyperaspis) (indoors): Scale predators (UC IPM). No indoor release conditions are sourced.
• Cryptolaemus montrouzieri (indoors): Will also feed on soft scales but prefers mealybugs.

From FGMN

• Cryptolaemus montrouzieri
  Will eat soft scale, though it prefers mealybugs

Timing: one good source

Sources (12)

1. Vegetable Planting Calendar, University of Maryland Extension
2. Freeze/Frost Occurrence Tables for Massachusetts, UMass Amherst Extension
3. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
4. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
5. Pest Notes: Scales, UC Statewide IPM Program
6. Oak Lecanium Scale, University of Maryland Extension
7. How and when do I bring my houseplants back indoors before winter?, Iowa State University Extension and Outreach
8. Keeping Your Houseplants Happy During Wintertime, University of Kentucky Cooperative Extension, Carter County
9. Biological Control of Mealybugs, UConn Extension IPM
10. Scales (Pest Notes), UC Statewide IPM Program
11. Scales on Houseplants, Cornell University (eCommons)
12. Scales, University of Wisconsin-Madison Extension Horticulture

Also called: scale insects, oystershell scale, euonymus scale, san jose scale, white peach scale

What you'll see: Small (under 1/8 inch), flat, crusty caps that can be lifted off the insect. They produce no honeydew, so plants are not sticky. Look for yellow spots or a general decline where colonies crowd.

Where it lives: Many species nationwide. Cited crawler dates are from Maryland and Kentucky.

In short: Euonymus/San Jose scale first crawlers: about late Apr to late May in zone 6 (typical last frost mid Apr), late Mar to late Apr in zone 8 and late May to mid Jun in zone 4. It moves with your local frost dates. Indoors: Year-round indoors.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Most armored scales have several generations a year and overwinter mainly as first-instar nymphs and adult females; in warm areas generations overlap.

Indoors and in greenhouses

Year-round indoors. Wisconsin notes armored scales rarely trouble greenhouse crops but are a concern in interiorscapes and conservatories. Armored species usually have several generations a year.

When it spikes:

• New or long-kept indoor plants: any time of year

Check again in: 7-14 days. Crawlers settle within 1–2 days of hatching. UC IPM uses weekly tape traps to time crawler activity.

What research says works

• Aphytis and Encarsia parasitic wasps (outdoors): Available commercially mainly for California red scale; otherwise conserve resident parasitoids during crawler periods.
• Chilocorus lady beetles (outdoors): Prey on armored scales; avoid persistent insecticides and dust.
• Aphytis and Encarsia parasitoids; Chilocorus and Rhyzobius lady beetles (indoors): Named natural enemies of scales (UC IPM). No indoor or greenhouse release conditions were found.

From FGMN

• Rhyzobius lophanthae
  The armored scale predator

Timing: rough estimate

Sources (8)

1. Vegetable Planting Calendar, University of Maryland Extension
2. Frost/Freeze climatology (Louisville, Lexington, Bowling Green, Frankfort), NOAA National Weather Service, Louisville KY
3. Armored Scale Insects on Trees and Shrubs, University of Maryland Extension
4. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
5. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
6. Pest Notes: Scales, UC Statewide IPM Program
7. Scales (Pest Notes), UC Statewide IPM Program
8. Scales, University of Wisconsin-Madison Extension Horticulture

Also called: leaf miners, spinach leafminer, beet leafminer, liriomyza

What you'll see: Winding, pale tunnels or blotches inside leaves, and white pinprick feeding and egg-laying punctures on the upper leaf surface. Adults are small, shiny black flies with yellow markings.

Where it lives: Beet/spinach leafminers on spinach, chard and beets in the North and mid-Atlantic. Vegetable leafminer (Liriomyza) is important in south and central Florida and only occasional in north Florida.

In short: First-generation flies lay eggs (beet/spinach leafminer): about early Apr to early Jun in zone 6 (typical last frost mid Apr), early Mar to early May in zone 8 and early May to late Jun in zone 4. It moves with your local frost dates. Indoors: A greenhouse pest that often arrives on incoming plants.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Vegetable leafminer is a serious tomato pest in south and central Florida during the growing season; no month-level peak found.

Indoors and in greenhouses

A greenhouse pest that often arrives on incoming plants. Warm conditions speed development, with egg to adult in as little as 14 days at 86°F.

When it spikes:

• Incoming plants: any time of year

Check again in: 7 days. Eggs hatch in 5–6 days, larvae mine for about 2 weeks, and egg to adult takes about 14 days at 86°F.

What research says works

• Diglyphus isaea (indoors): Works best above 68°F and at higher pest levels. Release weekly in the morning or evening. Remove sticky cards and replace them 3–4 days later.
• Dacnusa sibirica (indoors): Better adapted to cool (about 60°F), short-day, low-light conditions, so it suits winter.

From FGMN

• Diglyphus isaea
  Leafminer parasite; best above 68°F

Timing: one good source

Sources (5)

1. Vegetable Planting Calendar, University of Maryland Extension
2. Florida Vegetable Gardening Guide (VH021), UF/IFAS Extension
3. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension
4. Beet and Spinach Leafminers, University of Maryland Extension
5. Leafminer Pests of Greenhouse Crops, UConn Extension IPM

Also called: gnats, soil gnats, fungus flies, little black flies in plants

What you'll see: Small black, long-legged flies (about 1/16–1/8 in) flitting around pots and windows. They are weak fliers. Larvae are translucent and legless with a shiny black head, and they live in the top 2–3 inches of moist potting mix. Heavy infestations can leave slime trails on the soil surface. Adults are only a nuisance, but larvae can damage roots, especially on seedlings. To check for larvae, push 1/4-inch potato slices into the mix and look under them after a few days. Yellow sticky cards catch adults.

Where it lives: Not stated in sources. Mostly a problem in containers, seed starts and constantly wet media.

In short: New containers, transplants or seed starts while media is warm and wet: about mid Apr to mid May in zone 6 (typical last frost mid Apr), mid Mar to mid Apr in zone 8 and mid May to mid Jun in zone 4. It moves with your local frost dates. Indoors: Present year-round indoors, but nuisance levels peak in late fall and winter everywhere in the US.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No sourced outdoor seasonality.

Indoors and in greenhouses

Present year-round indoors, but nuisance levels peak in late fall and winter everywhere in the US. Shorter, cooler days slow plant growth and water use, so mix that is watered on a summer schedule stays wet and favors larvae. Plants returning indoors in fall can bring populations with them. Warm homes speed the cycle to about 3–4 weeks per generation.

When it spikes:

• Plants come back indoors and bring gnats in their pots: in zone 6, about mid Sep to mid Oct
• Low winter light plus a summer watering habit keeps soil wet: while the heat is on, roughly first frost to last frost

Check again in: 7-10 (sticky cards); expect a new generation in about 17-28 days days. At room temperature (65–75°F), egg to adult takes 3–4 weeks (CSU), or about 17 days at 75°F (UC IPM). Adults live 7–10 days. Bti does not persist indoors and is repeated about every 5 days (UC IPM).

What research says works

• Steinernema feltiae nematodes (outdoors): Drench media 2–3 days after planting and repeat every 7–10 days (FGMN). Water the media the day before; media must be above 50°F and below 80°F, with 60–70°F optimal. Apply early morning, evening or on cloudy days.
• Steinernema feltiae (beneficial nematode) (indoors): Apply as a soil drench to moist mix. Kills larvae in 1–4 days and stays active in the media for about 10–14 days, so several initial applications give longer control. Preventive drenches work best on cloudy days.
• Stratiolaelaps scimitus (Hypoaspis miles) (indoors): Use preventively at planting, before gnats build up. Needs media at 60°F or warmer (inactive below 59°F) that is moist but not waterlogged. Lives in the top 1/2 inch of mix. Takes about 18 days from egg to adult at 68°F. UC IPM calls Hypoaspis generally not a good choice for homes, so it suits greenhouses and indoor plant rooms better.
• Dalotia coriaria (rove beetle) (indoors): Best at 65–80°F and 50–85% RH. Release in the evening onto moist media. Egg to adult takes about 17 days at 79°F. Persists year-round once established in a greenhouse. Also eats thrips pupae.
• Bti (Bacillus thuringiensis israelensis), microbial (indoors): Drench for larvae. Repeat about every 5 days indoors.

From FGMN

• Sf Nematodes
  Kills larvae in the soil
• Stratiolaelaps scimitus
  Soil predator; best set up early
• Dalotia coriaria - Rove Beetle
  Rove beetle that settles in and keeps working
• Horiver Professional Sticky TrapsMonitoring
  Yellow cards to see if adults are dropping

Read our full fungus gnats guide

Timing: rough estimate

Sources (6)

1. How and when do I bring my houseplants back indoors before winter?, Iowa State University Extension and Outreach
2. Fungus Gnats as Houseplant and Indoor Pests, Colorado State University Extension
3. Fungus Gnats (Pest Notes), UC Statewide IPM Program
4. Biological Control of Western Flower Thrips, UConn Extension IPM
5. Biological Control of Fungus Gnats, UConn Extension IPM
6. Beneficial Nematodes fact sheet, UConn Extension IPM

Also called: slugs, snails

What you'll see: Ragged holes in leaves, shiny slime trails, and clusters of jelly-like eggs under pots and debris. Slugs (1/2–1.5 inches) hide by day and feed at night or after watering.

Where it lives: Wherever conditions are moist. In mild coastal California they are active year-round.

In short: Indoors: Feed and breed year-round in humid greenhouses.

Warm-winter areas (zones 9–11): Active year-round in mild coastal areas; most active in cool, moist weather. Snails go dormant (sealed) in hot, dry periods and hibernate in cold.

No frost-anchored dated calendar found. Bait and hand-pick in the evening after light watering. Nematode-based slug control was not covered in cited sources.

Indoors and in greenhouses

Feed and breed year-round in humid greenhouses. Most active in the evening, early morning, after irrigation and on cool, cloudy days.

When it spikes:

• Moist, cluttered greenhouse conditions: any time of year

Check again in: 7-10 days. Eggs hatch in under 10 days at 50°F. Iron phosphate bait kills in 3–6 days.

What research says works

• Decollate snail (Rumina decollata) (outdoors): Effective on young brown garden snails, but release is legally restricted to certain California counties and it should not be used near natural areas.
• Ground beetles, birds, toads; penned ducks/chickens (outdoors): Supplementary only.
• Phasmarhabditis hermaphrodita (slug nematode) (indoors): UConn says it is sold in Europe but not available in the US.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (2)

1. Pest Notes: Snails and Slugs, UC Statewide IPM Program
2. Managing Slugs in the Greenhouse, UConn Extension IPM

Also called: grubs, lawn grubs, grub worms, c-shaped grubs, masked chafer, oriental beetle, asiatic garden beetle

What you'll see: Brown, dying patches of lawn that peel back like a loose carpet because the roots are eaten, and spongy turf. Skunks, raccoons, crows or moles digging in the lawn can be a sign. Damage shows mostly in Apr–May and Sep–Oct.

Where it lives: Grubs of one kind or another occur across the US, but which species varies by region. Japanese beetle and northern masked chafer are the main damaging grubs in Pennsylvania. Japanese beetle is the most damaging grub in North Carolina, alongside masked chafers, May/June beetles, Asiatic garden beetle and green June beetle; oriental beetle occurs only in western NC there. Texas grubs are mostly June beetles and southern masked chafer. Japanese beetle is not established in most southern and western states.

In short: Eggs hatch; young grubs feed near the surface. Best window for nematodes: about early Aug to mid Sep in zone 6 (typical last frost mid Apr), early Jul to mid Aug in zone 8 and late Aug to late Sep in zone 4. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in July, August, September, October.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Zone 9b–10 Florida/Gulf Coast. The sugarcane grub (Tomarus subtropicus), a key Florida lawn grub, has one generation a year. Adults are active Apr–Jun (peak May–Jun) and eggs are present Jun–Jul. A Cape Coral/Punta Gorda study found eggs from about Jun 22 to Aug 5, first-instar grubs mostly in Jul–Aug, second instars Aug–Sep, and only third instars from early Oct. Third instars feed Oct–Apr, still feeding in January near Tampa. UF suggests preventive treatment against first instars in May–Jun. Lawn die-off usually shows in late summer to early fall. Texas: one generation a year for June beetles and southern masked chafer. Damage runs Jun–Oct depending on location, mostly midsummer to early fall, and shows earlier in warmer parts of the state. Preventive treatment goes on before grubs exceed 1/2 inch. Louisiana: eggs laid in midsummer hatch a few weeks later; injury appears mostly in early fall and early spring. For a 9b small-grub (egg-hatch) window, the best-sourced answer is roughly July–August. Peak months: July, August, September, October.

What research says works

• Beneficial nematodes, Heterorhabditis bacteriophora (preferred for grubs): Apply when young grubs are near the surface, about LSF+105 to +150 in zone 6 (late summer). Most researchers find Heterorhabditis works better than Steinernema on grubs, though results vary. H. bacteriophora is commercially available for Japanese beetle grubs. UC IPM describes it as searching deeper in soil for grubs and root weevils. Water at least 1/4 inch before and right after application. General extension guidance, from a greenhouse context, gives soil 50–80°F with 60–70°F optimal.
• Milky spore disease (Paenibacillus/Bacillus popilliae), Japanese beetle grubs only: NC State says apply in late Sep–early Oct to soil with pH 6–7. It takes 2–5 years to build up and has little value against other grub species. It has not been shown to work against Texas lawn grubs.
• Tiphia vernalis parasitic wasp (natural, not sold): Females parasitize Japanese beetle grubs in spring. Established from the Northeast south to NC. Support it with nectar sources such as maples, cherry and peonies.

From FGMN

• Hb Nematodes
  The grub nematode; apply to young grubs
• Triple Blend Nematodes
  Three nematodes when you have more than one soil pest

Timing: one good source

Sources (11)

1. White Grubs in Home Lawns, Penn State Extension
2. White Grubs in Turf, NC State Extension
3. Sugarcane Grub, Tomarus subtropicus (EENY318/IN593), University of Florida IFAS Extension (EDIS)
4. Seasonal phenology of Tomarus subtropicus in Florida turf (2006 meeting abstract), Entomological Society of America
5. White Grubs (Chafer Beetles), UF/IFAS Gardening Solutions
6. White Grubs in Texas Turfgrass, Texas A&M AgriLife Extension
7. Louisiana Home Lawn Series: White Grub, LSU AgCenter
8. Managing the Japanese Beetle: A Homeowner's Handbook, USDA APHIS
9. Beneficial Nematodes fact sheet, UConn Extension IPM
10. Parasitic Nematodes (garden controls), UC Statewide IPM Program (UC ANR)
11. Spring Frost/Freeze Climatology (Columbus avg last 32°F Apr 18, 1991–2020), NOAA National Weather Service, Wilmington OH

Also called: european chafer, chafer beetle

What you'll see: Lawn damage from root-feeding C-shaped grubs. The tan adults, about 1/2 inch long, swarm on warm evenings (above about 65°F) around sunset in early summer.

Where it lives: Known in NY (first US find, 1940), NJ, CT, PA, MA, RI, OH, MI, DE, WI (2013) and MN (2020), plus southern Ontario. States: NY, NJ, CT, PA, MA, RI, OH, MI, DE, WI, MN.

In short: Eggs hatch; young grubs near the surface (treatment window): about late Jul to late Aug in zone 6 (typical last frost mid Apr), late Jun to late Jul in zone 8 and mid Aug to mid Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Not present in frost-free regions per the listed distribution.

What research says works

• Heterorhabditis bacteriophora nematodes (general grub guidance): No European-chafer-specific nematode guidance found. Heterorhabditis is the general recommendation for grubs; apply on young grubs in August.

From FGMN

• Hb Nematodes
  Apply to young grubs in late summer

Timing: rough estimate

Sources (4)

1. White Grubs in Home Lawns, Penn State Extension
2. European Chafer, Minnesota Department of Agriculture
3. Parasitic Nematodes (garden controls), UC Statewide IPM Program (UC ANR)
4. Frost/Freeze probabilities, Albany NY (median Apr 27 / Oct 15), NOAA National Weather Service, Albany NY

Also called: june bugs, may beetles, june beetles, phyllophaga

What you'll see: Large brown beetles at porch lights in late spring. Grubs cause the worst root damage in spring, when they move up near the surface, and in years following heavy beetle flights.

Where it lives: Phyllophaga has over 100 species, each with a restricted range. They are found in Texas, Louisiana, North Carolina, Pennsylvania and Florida extension materials.

In short: Eggs hatch about 3 weeks after laying; young grubs in summer: about late May to late Jul in zone 6 (typical last frost mid Apr), mid Apr to mid Jun in zone 8 and mid Jun to mid Aug in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Texas: the May beetle Phyllophaga congrua has a 2-year cycle; adults fly late spring through summer, often after rain or irrigation. No Florida-specific Phyllophaga calendar was found.

What research says works

• Beneficial nematodes (Steinernema and Heterorhabditis): TAMU lists both genera as attacking white grubs; water 1/4 inch before and after. No species-specific timing found. Target small grubs in summer.
• Natural enemies: Tiphia and Myzinum wasps, Pyrgota fly, Cordyceps fungus: Occur naturally; not sold as a timed release.

From FGMN

• Hb Nematodes
  Apply to small summer grubs

Timing: rough estimate

Sources (3)

1. White Grubs, Phyllophaga spp. (IN202), University of Florida IFAS Extension (EDIS)
2. White Grubs in Texas Turfgrass, Texas A&M AgriLife Extension
3. Spring Frost/Freeze Climatology (Columbus avg last 32°F Apr 18, 1991–2020), NOAA National Weather Service, Wilmington OH

Also called: bluegrass billbug, hunting billbug

What you'll see: Yellow-brown patches that don't green up with watering. Grass stems pull out easily and break at the crown, and hollow stems are packed with fine sawdust-like frass. Damage often starts along sidewalks and driveways.

Where it lives: Bluegrass billbug is the New England cool-season lawn species. Hunting billbug is the Southeast warm-season species, a pest of zoysia and bermuda, with GA/NC/FL timing. Sources do not give a complete state list.

In short: Small larvae leaving stems (nematode window): about mid Jun to early Jul in zone 6 (typical last frost mid Apr), mid May to late May in zone 8 and early Jul to late Jul in zone 4. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in April, May, June.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Hunting billbug has about 6 overlapping generations a year in Florida. In south Georgia it is active year-round with all stages present at any time. Target adults in late winter–early spring and larvae in late spring–early summer, through June. Peak months: April, May, June.

What research says works

• Steinernema carpocapsae nematodes: Late June–early July in New England, timed to small larvae. Avoid hot, dry midday conditions and water in right away. Northeast trial data are limited; trials in Alabama and Ohio look better.
• S. feltiae or Heterorhabditis bacteriophora nematodes: Reported to control hunting billbug larvae; reliability depends on soil moisture and temperature.

From FGMN

• Sc Nematodes
  Time it to small larvae leaving the stems

Timing: one good source

Sources (3)

1. Billbugs in Lawns, UMass Amherst Extension
2. Hunting Billbug (C1173), University of Georgia Cooperative Extension
3. Freeze/Frost Occurrence Tables for Massachusetts (Worcester median Apr 27 / Oct 17), UMass Amherst Extension

Also called: lawn moths, webworms

What you'll see: Small brown patches that grow, with grass chewed short and ragged, silk-lined tunnels in the thatch, and green pellet droppings. Small tan moths fly up when you walk the lawn. A soapy-water flush brings caterpillars to the surface.

Where it lives: Several species occur on cool-season lawns in New England. Tropical sod webworm occurs on Florida warm-season lawns. No full state list was found.

In short: Summer generations: all stages present, peak damage. Treat young caterpillars 2–3 weeks after the moth-flight peak: about late Jun to late Aug in zone 6 (typical last frost mid Apr), late May to late Jul in zone 8 and mid Jul to mid Sep in zone 4. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in May, June, July, August, September, October.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Tropical sod webworm in Florida is most active spring through fall and can be found year-round in south Florida. Peak months: May, June, July, August, September, October.

What research says works

• Steinernema carpocapsae nematodes: Apply on small caterpillars, about 1/4 inch long, in the late afternoon or evening rather than midday, then water in at least 1/2 inch.
• Bt (Bacillus thuringiensis kurstaki): Same timing, on small caterpillars; stops feeding quickly but kills slowly.

From FGMN

• Sc Nematodes
  On small caterpillars, late in the day

Timing: one good source

Sources (3)

1. Sod Webworms, UMass Amherst Extension
2. Tropical Sod Webworm, UF/IFAS Gardening Solutions
3. Freeze/Frost Occurrence Tables for Massachusetts (Worcester median Apr 27 / Oct 17), UMass Amherst Extension

Also called: armyworms

What you'll see: Lawns stripped brown seemingly overnight, with ragged chewed blades and lots of green frass. Birds keep feeding in one area, wasps hunt over the lawn, and egg masses appear on light-colored walls or posts.

Where it lives: Overwinters only in south Florida and Texas. Moths ride weather fronts north each spring and summer and cannot survive Alabama or Georgia winters. Damage concentrates in the Southeast; sources do not give a northern limit. Dated windows are shown for zones 7–9 (Alabama reference); farther north, outbreaks come later and less often, after moths arrive on weather fronts.

In short: Main lawn outbreaks (late summer–early fall): about late Jul to late Oct in zone 8 (typical last frost mid Mar), mid Jul to early Oct in zone 7 and mid Aug to early Nov in zone 9. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Year-round source populations in south Florida and Texas. No sourced peak months for those areas.

What research says works

• Bt (Bacillus thuringiensis): Listed as a homeowner option; apply early or late in the day when larvae are active.
• Natural predators (birds, wasps, fire ants): They often reduce numbers before damage shows.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. Controlling Fall Armyworms on Lawns and Turf, Alabama Cooperative Extension System
2. Armyworms (turfgrass pests), University of Georgia Extension
3. First Fall Freeze Climatology, Birmingham AL (avg Nov 9), NOAA National Weather Service, Birmingham AL

Also called: leatherjackets, crane flies, mosquito hawks, daddy long legs larvae

What you'll see: Thin, yellowing or bare lawn patches in late winter and spring, often in wet spots. Birds and animals peck or dig at the turf, and empty pupal cases stick up after adults emerge. Swarms of large mosquito-like flies appear in late summer and fall.

Where it lives: Cornell says both species are now established across most of the continental US. They were first found in NY in 2004 and are long-standing pests in the Pacific Northwest.

In short: Young larvae near the surface (preventive window): about early Sep to early Nov in zone 6 (typical last frost mid Apr), early Oct to early Dec in zone 8 and mid Aug to mid Oct in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

What research says works

• Natural predators (starlings, robins, predatory insects): Often reduce larvae below damaging levels by spring.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. European Crane Flies (Tipula paludosa and Tipula oleracea), Cornell University / NYS IPM
2. Lawn and Turf: European Crane Fly, Washington State University HortSense
3. Frost/Freeze probabilities, Albany NY (median Apr 27 / Oct 15), NOAA National Weather Service, Albany NY

Also called: tawny mole cricket

What you'll see: Raised, squishy tunnels just under the lawn surface and thinning or dead grass, worst in sandy soil. A soapy-water flush brings crickets up.

Where it lives: Tawny and southern mole crickets range from North Carolina south to Florida and west to Texas, and are worst in sandy coastal-plain soils. Isolated populations are in Arizona and California. Shortwinged mole crickets are a problem in FL and GA. States: NC, SC, GA, FL, AL, MS, LA, TX, AZ, CA.

In short: Eggs hatch; small nymphs (most susceptible stage, best treatment window): about early May to early Aug in zone 8 (typical last frost mid Mar), late May to late Aug in zone 7 and early Apr to early Jul in zone 9. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in April, May, September, October.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Florida: overwintering tawny adults lay eggs April to early June. Nymphs grow through summer and begin to mature in September. Peak months: April, May, September, October.

What research says works

• Steinernema scapterisci nematodes: UF says apply in spring or fall and that it can establish permanently. Clemson says no commercial product is currently available. Check availability before recommending it.
• Larra bicolor wasp (plant nectar flowers) and Ormia depleta fly: Natural or established biocontrols in Florida and the Southeast; support the wasp with nectar plants.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. Mole Crickets, UF/IFAS IPM
2. Mole Crickets Information, Clemson University Turf & Ornamental IPM
3. Spring Frost/Freeze dates, Columbia SC (avg last freeze Mar 16), NOAA National Weather Service, Columbia SC

Also called: southern chinch bug, hairy chinch bug

What you'll see: Yellowing patches in sunny, hot spots that turn brown and spread outward, easily mistaken for drought. A water-filled can pushed into the edge of a patch floats out the tiny bugs.

Where it lives: Hairy chinch bug affects northern cool-season lawns. Southern chinch bug is a major St. Augustinegrass pest in southern states; about a third of Florida St. Augustine lawns have it. No full state list was found.

In short: Nymphs feed; damage from June, with a second generation in August: about late May to late Aug in zone 6 (typical last frost mid Apr), late Apr to late Jul in zone 8 and mid Jun to mid Sep in zone 4. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in March, April, May, June, July, August, September, October.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Southern chinch bug: north Florida active about March–October; south Florida has many more generations and continuous activity. Peak months: March, April, May, June, July, August, September, October.

What research says works

• Big-eyed bugs (Geocoris), conserved rather than bought: Natural predators of nymphs and adults; avoid broad-spectrum sprays.
• Egg parasitoid wasp Eumicrosoma benefica (natural): Occurs naturally.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. Hairy Chinch Bug fact sheet, University of New Hampshire Extension
2. Southern Chinch Bug (EDIS), University of Florida IFAS Extension
3. Freeze/Frost Occurrence Tables for Massachusetts (Worcester median Apr 27 / Oct 17), UMass Amherst Extension

Also called: fleas, flea larvae

What you'll see: Pets scratching; tiny dark jumping insects on pets or socks in shady spots where pets rest. Larvae live in shaded, humid, still-air spots such as under decks and in dog runs.

Where it lives: Distribution not stated in retrieved sources.

In short: No extension source with a seasonal flea calendar was found, so no stages are given. Outdoor treatment is mainly for severe infestations; controlling fleas on the pet and indoors comes first.

Warm-winter areas (zones 9–11): No sourced seasonal pattern. The life cycle takes about 30–75 days depending on temperature and humidity.

No extension source with a seasonal flea calendar was found, so no stages are given. Outdoor treatment is mainly for severe infestations; controlling fleas on the pet and indoors comes first.

What research says works

• Steinernema carpocapsae nematodes: Spray on soil where pets rest, targeting flea larvae. Works best in moist, sandy soil and may be less effective elsewhere. No seasonal timing given; treat shaded pet areas, not the whole yard.

From FGMN

• Sc Nematodes
  On moist, shady spots where pets rest

Timing: rough estimate

Sources (1)

1. Cat Flea, University of Georgia IPM

Also called: deer ticks, blacklegged ticks

What you'll see: Tiny ticks (nymphs are poppy-seed sized) on people or pets after time in leaf litter, brush or tall grass edges.

Where it lives: Timing comes from Minnesota and is shown for zones 3–7 only. Tick species and seasons differ in the South; check your state health department.

In short: Nymphs active (highest bite risk): about mid May to late Jun in zone 6 (typical last frost mid Apr), mid Jun to mid Jul in zone 4 and early May to mid Jun in zone 7. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No sourced data.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (2)

1. Ticks in Minnesota, Minnesota Department of Health
2. First Fall Freeze Information, Twin Cities (typically Oct 1–10), NOAA National Weather Service, Twin Cities MN

Also called: mosquito larvae, wrigglers

What you'll see: Wriggling 'tumblers' in standing water in buckets, saucers, tires, gutters, birdbaths and tarps.

Where it lives: Container breeders such as the Asian tiger mosquito use any container holding rainwater; floodwater species follow spring rains.

In short: Larval season: dump standing water weekly: about mid Apr to late Oct in zone 6 (typical last frost mid Apr), mid Mar to mid Nov in zone 8 and mid May to late Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): In Oklahoma, over 60 species are active from March to the first frost in November, with floodwater species peaking after spring rains (Apr-May) and permanent-water species later in summer. No frost-free calendar found.

What research says works

• Biorational larvicide (Bti 'Mosquito Dunks'-type products): Use in water that can't be dumped, all larval season, per the label. Kills only mosquito larvae.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (3)

1. Vegetable Planting Calendar, University of Maryland Extension
2. Mosquitoes (Digital Diagnostics), Oklahoma State University Extension
3. MDA asks residents to act now to help control mosquito populations (Apr 13, 2023), Maryland Department of Agriculture

Also called: black cutworm

What you'll see: Pock-marked spots like golf-ball marks with a small burrow, grass clipped around the hole and green frass in turf. In gardens, seedlings are cut off at the soil line overnight.

Where it lives: Black cutworm moths can't survive New England winters. They overwinter to the south (about Maryland to the Carolinas) and fly back north on spring weather fronts. They are found in turf and garden settings nationally.

In short: Larvae feeding; most obvious damage: about late May to late Aug in zone 6 (typical last frost mid Apr), late Apr to late Jul in zone 8 and mid Jun to mid Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Overwinters in the South. No sourced generation count or peak months for frost-free zones.

What research says works

• Steinernema carpocapsae nematodes: Target small caterpillars about 1/4 inch long, or 2–3 weeks after the peak moth flight. Apply late in the day and water in 1/2 inch. UC IPM also lists it for cutworms.
• Bt kurstaki: On small caterpillars; stops feeding.

From FGMN

• Sc Nematodes
  On small caterpillars, late in the day

Timing: one good source

Sources (3)

1. Parasitic Nematodes (garden controls), UC Statewide IPM Program (UC ANR)
2. Cutworms (turf), UMass Amherst Extension
3. Freeze/Frost Occurrence Tables for Massachusetts (Worcester median Apr 27 / Oct 17), UMass Amherst Extension

Also called: cabbage maggot, onion maggot

What you'll see: Transplants of cabbage, broccoli or radish wilt and stunt, or onion seedlings collapse. Small white maggots tunnel in roots or bulbs, often followed by rot.

Where it lives: Each species stays on its own crop family. Distribution was not stated beyond New England and Wisconsin sources.

In short: First-generation flies lay eggs at the base of plants (main damage generation): about mid Apr to late May in zone 6 (typical last frost mid Apr), mid Mar to late Apr in zone 8 and mid May to mid Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No sourced data.

What research says works

• Steinernema feltiae nematodes: Effective against cabbage maggot even at 50°F soil. Apply as a pre-transplant soak, in transplant water or as a post-plant drench. A post-plant drench is needed if flight starts more than a week after transplanting. Keep soil moist.
• Predatory ground beetles and natural fungal disease: Conserve them by avoiding broadcast soil insecticides.

From FGMN

• Sf Nematodes
  In transplant water or as a drench at planting

Timing: one good source

Sources (3)

1. Onion Maggot, UMass Amherst Extension Vegetable Program
2. Degree Days for Common Fruit and Vegetable Insect Pests, University of Wisconsin–Madison Extension
3. Freeze/Frost Occurrence Tables for Massachusetts (Worcester median Apr 27 / Oct 17), UMass Amherst Extension

Also called: click beetle larvae

What you'll see: Seeds fail to come up; seedlings are stunted with small holes in stems; potatoes and root crops have narrow tunnels. Larvae are shiny, tough and yellow-brown, in the top 6 inches of soil.

Where it lives: Found almost anywhere, especially old fields and grass pastures. Worst in poorly drained soil within 1–4 years after sod is turned under.

In short: Spring planting: larvae feed on seeds and seedlings in cool, moist soil: about mid Apr to early Jun in zone 6 (typical last frost mid Apr), mid Mar to early May in zone 8 and mid May to late Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No sourced data.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (1)

1. Wireworms (Garden Facts), University of Wisconsin–Madison Extension

Also called: SVB, vine borer

What you'll see: Squash or pumpkin vines suddenly wilt at midday. Holes near the base of the stem are packed with sawdust-like orange frass. Red-and-black day-flying moths appear around the plants.

Where it lives: Distribution was not stated in the retrieved sources (Massachusetts and Wisconsin extension pages). Verify the range before publishing.

In short: Eggs hatch; target hatching larvae before they bore in: about late Jun to late Jul in zone 6 (typical last frost mid Apr), late May to late Jun in zone 8 and mid Jul to late Aug in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No sourced data. Massachusetts sees a possible second flight in late August in warm years.

What research says works

• Bt (Bacillus thuringiensis, aizawai strain preferred): Spray stem bases at egg hatch.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. Squash Vine Borer, UMass Amherst Extension Vegetable Program
2. Degree Days for Common Fruit and Vegetable Insect Pests, University of Wisconsin–Madison Extension
3. Freeze/Frost Occurrence Tables for Massachusetts (Worcester median Apr 27 / Oct 17), UMass Amherst Extension

Also called: striped cucumber beetle, spotted cucumber beetle

What you'll see: Yellow beetles with black stripes or spots chewing seedlings, leaves and flowers. Cucumber and melon vines that suddenly wilt may have bacterial wilt, which these beetles spread.

Where it lives: Striped cucumber beetle overwinters locally; spotted cucumber beetle migrates north from the southern US each summer. Also a listed pest in Florida gardens.

In short: Striped beetles arrive on young cucurbits – protect seedlings (cotyledon to 3rd leaf): about late May to mid Jun in zone 6 (typical last frost mid Apr), late Apr to mid May in zone 8 and late Jun to early Jul in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Listed as a Florida garden pest; no month-level pattern found.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. Minnesota climate facts (freeze dates), Minnesota Department of Natural Resources
2. Cucumber beetles, University of Minnesota Extension
3. Florida Vegetable Gardening Guide (VH021), UF/IFAS Extension

What you'll see: Bronze egg clusters on leaf undersides, gray bugs hiding under leaves and at the plant base, and yellow spots that turn brown, with wilting runners.

Where it lives: Pest of squash and pumpkins; cited timing from Minnesota.

In short: Egg-laying period – crush egg masses, treat young nymphs: about late May to late Jul in zone 6 (typical last frost mid Apr), late Apr to late Jun in zone 8 and late Jun to mid Aug in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (2)

1. Minnesota climate facts (freeze dates), Minnesota Department of Natural Resources
2. Squash bugs, University of Minnesota Extension

What you'll see: Leaves riddled with tiny round 'shot holes', and very small shiny beetles that jump when disturbed. Seedlings can be stunted.

Where it lives: Many species on brassicas, eggplant, potato and tomato; cited timing from Minnesota.

In short: Spring seedling damage window: about mid Apr to late May in zone 6 (typical last frost mid Apr), mid Mar to late Apr in zone 8 and mid May to mid Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

What research says works

• Native braconid wasp Microctonus vittatae; lacewing larvae: Not sold commercially; conserve. Lacewing larvae have been seen feeding on flea beetles.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (2)

1. Minnesota climate facts (freeze dates), Minnesota Department of Natural Resources
2. Flea beetles, University of Minnesota Extension

Also called: potato bugs

What you'll see: Yellow-and-black striped beetles, orange egg clusters under leaves, and humpbacked reddish larvae with black spots stripping foliage.

Where it lives: Potato, eggplant and tomato pest. In Florida it is mainly a problem in the northern half of the state.

In short: Phenology cue, not a date: overwintered adults emerge as potato plants emerge; 4th-instar larvae do ~75% of the damage, which is most critical once tubers bulk after flowering. No dated calendar was found, so stages are empty.

Warm-winter areas (zones 9–11): Mainly northern Florida; no month-level data.

Phenology cue, not a date: overwintered adults emerge as potato plants emerge; 4th-instar larvae do ~75% of the damage, which is most critical once tubers bulk after flowering. No dated calendar was found, so stages are empty.

What research says works

• Bt (and neem): Organic option effective only on small larvae at low populations. The source does not name the tenebrionis strain.
• Lady beetles, predatory stink bugs (egg predators); Beauveria bassiana: Predators eat eggs but have limited effect; Beauveria products are still being researched.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (2)

1. Colorado potato beetles, University of Minnesota Extension
2. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension

What you'll see: Copper-colored lady-beetle-like adults with 16 spots, yellow spiny larvae under leaves, and lacy skeletonized bean leaves.

Where it lives: Sources cover New England and the mid-Atlantic, where Pediobius releases have a good track record. The wider US range was not verified in this review. States: MA, CT, NJ, MD, DE, PA, VA.

In short: Adults move into beans and lay yellow egg clusters: about late May to late Jun in zone 6 (typical last frost mid Apr), late Apr to late May in zone 8 and late Jun to late Jul in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

What research says works

• Pediobius foveolatus (parasitic wasp): Release when eggs are first found, ideally timed to egg hatch, and again 1–2 weeks later (2–3 releases for succession plantings). Home gardens need at least 10–15 mummies. Frost kills the wasp, so re-release every year.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (2)

1. Freeze/Frost Occurrence Tables for Massachusetts, UMass Amherst Extension
2. Mexican Bean Beetle, UMass Amherst Vegetable Program

Also called: cabbage worms, cabbage white, cabbage looper, diamondback moth

What you'll see: Ragged holes in cabbage, kale and broccoli leaves with green-brown frass in the heads. Diamondback larvae leave 'windowpane' patches on leaf undersides.

Where it lives: Imported cabbageworm overwinters locally. Cabbage looper migrates north from the South each summer. Diamondback moth overwinters as adults, with heavy losses in cold winters. All three are listed Florida garden pests.

In short: Peak caterpillar pressure (2nd gen cabbageworm; cabbage looper arrives): about early Jul to early Sep in zone 6 (typical last frost mid Apr), late May to early Aug in zone 8 and late Jul to late Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): In Florida these caterpillars are pests of fall-to-spring cole crops; no month-level peak found.

What research says works

• Bt (Bacillus thuringiensis kurstaki or aizawai): Very effective on early-instar larvae with good coverage; use early to mid-season. Diamondback Bt resistance has been documented elsewhere in the US.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. When is the last frost?, University of Wisconsin-Madison SSEC (The Weather Guys)
2. Florida Vegetable Gardening Guide (VH021), UF/IFAS Extension
3. Caterpillar Pests of Cole Crops (A3724), University of Wisconsin Extension

Also called: tomato hornworm

What you'll see: Big green caterpillars with a horn at the tail, rapid stripping of leaves (sometimes fruit), and dark green or black droppings on leaves below. White rice-like cocoons on a hornworm mean it is parasitized.

Where it lives: Pest of tomato, pepper, eggplant and potato; listed for Florida and Minnesota gardens.

In short: UMN gives the life cycle (pupae overwinter, moths emerge in spring, 2nd generation midsummer) but no dates, so no anchored stages are given.

Warm-winter areas (zones 9–11): Listed Florida tomato pest; no month-level data.

UMN gives the life cycle (pupae overwinter, moths emerge in spring, 2nd generation midsummer) but no dates, so no anchored stages are given.

What research says works

• Cotesia congregata (braconid wasp): Leave hornworms carrying white cocoons in the garden so the wasps emerge.
• Bt kurstaki: Works best on very young caterpillars.
• Lady beetles, green lacewings (eggs/young larvae); paper wasps: Conserve.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (2)

1. Tomato hornworms, University of Minnesota Extension
2. Florida Vegetable Gardening Guide (VH021), UF/IFAS Extension

Also called: tomato fruitworm

What you'll see: Caterpillar feeding and frass at sweet-corn ear tips, with moldy kernels. In tomato and pepper, holes bored into fruit.

Where it lives: Overwinters only in warmer climates and migrates north each year; in Utah it overwinters in the central and southern parts and flies into the north.

In short: Main moth flights – peak ear damage: about late Jul to late Sep in zone 6 (typical last frost mid Apr), late Jun to late Aug in zone 8 and mid Aug to late Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Year-round survival in warm areas. Southern Utah's first flight starts 3–4 weeks earlier, with a possible 4th generation. Florida lists it as tomato fruitworm.

What research says works

• Trichogramma egg parasitoid wasps: Release timed to egg laying on fresh silk; USU reports limited success in Utah, and timing is critical.
• Horticultural mineral oil on silks: Apply to silk tips every 2–3 days after silking; suppression only.
• Bt: Not effective inside corn ears; works on tomato/pepper if reapplied every 2–3 days.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (3)

1. Suggested Vegetable Planting Dates for the Wasatch Front, Utah State University Extension
2. Corn Earworm, Utah State University Extension
3. Insect management for tomatoes, peppers and eggplant (IN169), UF/IFAS Extension

Also called: SWD, fruit flies in berries

What you'll see: Soft, sunken, leaky spots on ripe raspberries, blueberries, cherries and similar fruit, with tiny white maggots inside, often a day or two after picking.

Where it lives: Cited timing from Minnesota. SWD is widely reported in US fruit regions, but a range map was not reviewed.

In short: Peak populations: about mid Aug to mid Oct in zone 6 (typical last frost mid Apr), early Sep to early Nov in zone 8 and mid Jul to mid Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (2)

1. Minnesota climate facts (freeze dates), Minnesota Department of Natural Resources
2. Spotted wing drosophila, University of Minnesota Extension

Also called: jap beetles

What you'll see: Metallic green and copper beetles in groups skeletonizing leaves into lace, especially on roses, linden, grape and birch.

Where it lives: Per UMN: throughout the eastern US except Florida, and spreading west. The state list is an approximation of 'eastern US'. Grubs are covered separately. The state list is partial: populations also exist in some western-edge states. States: ME, NH, VT, MA, RI, CT, NY, NJ, PA, DE, MD, DC, VA, WV, NC, SC, GA, AL, MS, TN, KY, OH, IN, IL, MI, WI, MN, IA, MO.

In short: Peak adult feeding: about late Jun to late Jul in zone 6 (typical last frost mid Apr), late May to late Jun in zone 8 and late Jul to mid Aug in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Not present in Florida per UMN.

What research says works

• Winsome fly (Istocheta aldrichi): Lays white eggs on adult beetles in summer. Leave beetles with white dots alive.
• Bt galleriae (Btg): Moderately effective on adults, about 1–2 weeks' protection; not harmful to bees.

From FGMN

• Hb Nematodes
  Nothing we sell targets adult beetles. Treating grubs in late summer cuts your own lawn's next crop, but beetles still fly in from nearby yards.

Timing: well documented

Sources (3)

1. Minnesota climate facts (freeze dates), Minnesota Department of Natural Resources
2. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
3. Japanese beetles, University of Minnesota Extension

Also called: root weevils, vine weevil, strawberry root weevil

What you'll see: Adults chew notches (C-shaped) into leaf edges at night; this is mostly cosmetic. Larvae eat roots and can girdle stems at the soil line, so yews, rhododendrons and potted perennials wilt and die, often discovered in spring.

Where it lives: Range runs from Maine to the Carolinas and west to Washington and Oregon; it is in all Ohio counties and spreads on nursery plants. The list gives only states named or clearly inside that range; states in between are likely present but not listed in sources. States: ME, NH, VT, MA, RI, CT, NY, NJ, PA, DE, MD, VA, NC, SC, OH, MI, WA, OR.

In short: Young larvae feeding on roots. Best nematode window, mainly for container plants, while soil is above 55°F: about mid Aug to late Sep in zone 6 (typical last frost mid Apr), early Sep to late Oct in zone 8 and mid Jul to early Sep in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free outdoor timing found. In warm greenhouses or pots, pupation happens in Jan–Feb and adults appear in Mar–Apr.

What research says works

• Heterorhabditis bacteriophora nematodes: Larvae in late summer or fall, with soil above 55°F. Listed for black vine weevil larvae by UConn and UC IPM.
• Steinernema carpocapsae or S. kraussei nematodes: UConn lists both for black vine weevil larvae. OSU notes nematodes work best in containers. In landscapes, pull back mulch and water before and after, and expect variable results.

From FGMN

• Hb Nematodes
  Young larvae, soil above 55°F
• Sc Nematodes
  Also listed for weevil larvae, best in containers

Timing: one good source

Sources (4)

1. Black Vine Weevil (ENT-49), Ohio State University Extension (Ohioline)
2. Beneficial Nematodes fact sheet, UConn Extension IPM
3. Parasitic Nematodes (garden controls), UC Statewide IPM Program (UC ANR)
4. Spring Frost/Freeze Climatology (Columbus avg last 32°F Apr 18, 1991–2020), NOAA National Weather Service, Wilmington OH

Also called: conifer mites

What you'll see: Older inner needles look speckled, yellowish or rusty and may drop, with fine silk among the needles. Tap a branch over white paper to see tiny moving mites.

Where it lives: Wherever spruce, arborvitae, juniper, hemlock and other conifers are planted; cited timing is from Pennsylvania and Kentucky. Range not mapped in cited sources.

In short: Spring control window: about late Apr to mid May in zone 6 (typical last frost mid Apr), late Mar to mid Apr in zone 8 and late May to mid Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Cool-season pest active spring and fall, quiet in summer heat. No frost-free US data found; host conifers are uncommon in zones 9b-11.

What research says works

• Amblyseius andersoni (cool-tolerant predatory mite): Active 42–104°F and usable outdoors; release while mite numbers are low. Low confidence: the source does not test it against spruce spider mite.

From FGMN

• Amblyseius andersoni
  Cool-tolerant predator; untested on this exact mite

Timing: one good source

Sources (5)

1. First/Last Freeze Dates - Philadelphia area climate sites, NOAA National Weather Service, Mount Holly NJ
2. Frost/Freeze climatology (Louisville, Lexington, Bowling Green, Frankfort), NOAA National Weather Service, Louisville KY
3. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
4. Spruce Spider Mite, Penn State Extension
5. Biological Control of Spider Mites (greenhouse fact sheet), UConn Extension IPM

Also called: chili thrips, scirtothrips

What you'll see: Bronzing along leaf veins, upward-cupped or distorted new leaves and buds, browning, and leaf drop. The damage is usually noticed before the tiny insects.

Where it lives: Invasive. Established in Florida since 2005 (first on roses in Palm Beach County), reported in Texas and Louisiana, and first detected in Georgia in 2022. States: FL, GA, LA, TX.

In short: Heavy infestations on new flush in hot, dry weather: about early Jun to early Oct in zone 8 (typical last frost mid Mar) and early May to early Sep in zone 9. It moves with your local frost dates. In frost-free areas (zones 10–11) it peaks in June, July, August, September.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Breeds continuously in warm weather (egg to adult ~18–20 days at 77–81°F); worst during prolonged hot, dry spells on tender new growth. Peak months: June, July, August, September.

What research says works

• Amblyseius swirskii (predatory mite): Has shown some effectiveness in pepper studies; deploy on new flush before populations climb.
• Minute pirate bug (Orius insidiosus), big-eyed bugs (Geocoris): Feed on all thrips stages; conserve by avoiding broad-spectrum sprays.

From FGMN

• Amblyseius swirskii
  Release on new flush before numbers climb

Read our full chilli thrips guide

Timing: one good source

Sources (4)

1. Average last freeze dates (Atlanta, Athens, Macon, Columbus), NOAA National Weather Service, Peachtree City GA
2. Frost/Freeze information - average first fall freeze, NOAA National Weather Service, Peachtree City GA
3. Chilli Thrips on Blueberries in Florida (ENY-2053 / IN1298), UF/IFAS Extension
4. Chilli thrips (Scirtothrips dorsalis), University of Georgia IPM

Also called: azalea lace bug

What you'll see: Pale white-stippled upper leaf surfaces, worst on shrubs in full sun, with black tar-like spots and cast skins on leaf undersides.

Where it lives: On azalea, rhododendron, Pieris, hawthorn, sycamore, oak and other hosts; cited timing from Georgia, Kentucky, Maryland and Massachusetts. Range not mapped in cited sources.

In short: Azalea lace bug overwintered eggs hatch (Georgia): about mid Apr to early May in zone 6 (typical last frost mid Apr), mid Mar to early Apr in zone 8 and mid May to early Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Azalea lace bug has at least four generations a year in Georgia, each taking about a month; hawthorn-type lace bugs have 3–4.

What research says works

• Predatory mirid plant bugs and egg-parasitic mymarid wasps: Check for red-and-black mirid predators and egg exit holes before spraying; if present, hold off.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (6)

1. Average last freeze dates (Atlanta, Athens, Macon, Columbus), NOAA National Weather Service, Peachtree City GA
2. Frost/Freeze information - average first fall freeze, NOAA National Weather Service, Peachtree City GA
3. Frost/Freeze climatology (Louisville, Lexington, Bowling Green, Frankfort), NOAA National Weather Service, Louisville KY
4. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
5. Lace Bugs on Trees and Shrubs, University of Maryland Extension
6. Lace Bugs (Landscape Pest Management), University of Georgia Extension

What you'll see: Spindle-shaped bags of silk and plant bits hanging from branches, with browned, chewed evergreen foliage.

Where it lives: UConn describes it as a pest across the eastern US on arborvitae, juniper, cedar, pine and many deciduous trees. Exact western limit not verified.

In short: Young larvae, while bags are small: the easiest time to treat: about early Jun to early Jul in zone 6 (typical last frost mid Apr), early May to early Jun in zone 8 and early Jul to early Aug in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

What research says works

• Bt kurstaki: Spray soon after hatch while larvae and bags are small; effectiveness drops later in summer. Hand-pick bags from fall to early spring.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: well documented

Sources (3)

1. Freeze/Frost Occurrence Tables for Connecticut, UMass Amherst Extension
2. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
3. Bagworm fact sheet, UConn Home & Garden Education Center

What you'll see: Blistered, puffy boxwood leaves that turn yellow-brown, with orange maggots inside. In spring, small orange flies swarm the shrubs.

Where it lives: Wherever boxwood is grown; cited timing from Pennsylvania, Massachusetts and Kentucky. Range not mapped in cited sources.

In short: Adult flies emerge and lay eggs (weigela in bloom): about late Apr to late May in zone 6 (typical last frost mid Apr), late Mar to late Apr in zone 8 and late May to late Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (4)

1. Freeze/Frost Occurrence Tables for Massachusetts, UMass Amherst Extension
2. First/Last Freeze Dates - Philadelphia area climate sites, NOAA National Weather Service, Mount Holly NJ
3. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
4. Boxwood Leafminer, Penn State Extension

Also called: lanternfly, SLF

What you'll see: Black-and-white spotted nymphs that later turn red, then large gray-pink planthoppers with red hindwings massing on tree-of-heaven, grape and maples, with honeydew and sooty mold below. Mud-like gray egg masses on flat surfaces in fall and winter.

Where it lives: States with spotted lanternfly quarantines or detections (CDFA list, July 2025, plus New Hampshire's first detection in August 2026 and DC). Quarantines cover counties, not whole states, and the list keeps growing. States: CT, DC, DE, GA, IL, IN, KY, MA, MD, MI, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, WV.

In short: Egg laying – scrape and destroy egg masses (through winter): about late Sep to early Nov in zone 6 (typical last frost mid Apr), mid Oct to late Nov in zone 8 and late Aug to early Oct in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Not established in frost-free US areas per the cited quarantine list.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: well documented

Sources (4)

1. First/Last Freeze Dates - Philadelphia area climate sites, NOAA National Weather Service, Mount Holly NJ
2. National Pest Alert: Spotted Lanternfly, USDA-NIFA Regional IPM Centers / Penn State / PA Dept. of Agriculture (hosted by NC State)
3. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
4. Spotted Lanternfly - List of Quarantine Infestations (updated 7/28/25), California Department of Food and Agriculture

Also called: red lily beetle

What you'll see: Bright red beetles on lilies and fritillaria, then slug-like larvae covered in their own black excrement, chewing holes until stems are bare.

Where it lives: Introduced in Massachusetts in 1992 and spread through New England and New York; UMass expects it to spread across much of North America. States: ME, NH, VT, MA, RI, CT, NY.

In short: Egg laying – crush egg rows, hand-pick adults: about late Apr to late May in zone 6 (typical last frost mid Apr), late Mar to late Apr in zone 8 and late May to late Jun in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): Not documented in frost-free areas.

What research says works

• Tetrastichus setifer, Lemophagus errabundus, Diaparsis jucunda (larval parasitoid wasps): Released by researchers from 1999 to 2016 in New England and New York and established at several sites (e.g., Wellesley MA, Cumberland RI). Not a garden-release product per cited source.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (2)

1. Freeze/Frost Occurrence Tables for Massachusetts, UMass Amherst Extension
2. Lily Leaf Beetle, UMass Amherst Extension

Also called: roseslug, pear slug, sawflies

What you'll see: Slimy slug-like larvae on leaves that eat away the leaf surface, leaving brown, see-through 'windows' and a scorched look.

Where it lives: Cited timing from Massachusetts and Kentucky. Pear slug attacks pear, cherry, plum, cotoneaster, hawthorn, mountain ash and serviceberry.

In short: Roseslug larvae feeding: about mid May to late Jun in zone 6 (typical last frost mid Apr), mid Apr to late May in zone 8 and mid Jun to late Jul in zone 4. It moves with your local frost dates.

Outdoors: when, by USDA zone

Zone columns use typical frost dates for the middle of each zone. Enter your ZIP above for your own dates.

Warm-winter areas (zones 9–11): No frost-free data found.

What research says works

• Natural enemies (Trichogramma minutum egg parasitism reported; lacewing larvae, predatory bugs): Effectiveness against these sawflies in North America is not established. Note: Bt kurstaki does not work on sawfly larvae.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (5)

1. Freeze/Frost Occurrence Tables for Massachusetts, UMass Amherst Extension
2. ENTFACT-447: Calendar for Common Kentucky Shade Tree and Woody Ornamental Pests, University of Kentucky Entomology
3. Professional Insect & Mite Guide - Monthly Almanacs, UMass Amherst Extension
4. Pear sawfly (Caliroa cerasi) - Landscape Insect & Mite Guide, UMass Amherst Extension
5. Roseslug and curled rose sawfly - Landscape Insect & Mite Guide, UMass Amherst Extension

Also called: broad mites, cyclamen mites

What you'll see: Too small to see without strong magnification. New growth looks twisted, hardened, cupped or bronzed underneath. Buds die or blacken, and flowers fail to open. The damage often appears suddenly in spots and is easily mistaken for herbicide injury, nutrient deficiency or cold damage. With a 20x lens, broad mite eggs can sometimes be seen as tiny eggs covered in white bumps.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: Cyclamen mites prefer cool, very humid conditions (about 60°F, 80–90% RH), and severe outbreaks often come in fall and winter.

Indoors and in greenhouses

Cyclamen mites prefer cool, very humid conditions (about 60°F, 80–90% RH), and severe outbreaks often come in fall and winter. Broad mites prefer warm, humid conditions (70–80°F, 80–90% RH). Both spread on hands, clothing, contact between plants and propagation material, and broad mites also hitch rides on whiteflies.

When it spikes:

• Cool, humid fall and winter (cyclamen mites): while the heat is on, roughly first frost to last frost
• New or propagated plants brought in: any time of year

Check again in: 7 days. Broad mites can go from egg to adult in about 1 week, and broad mite eggs hatch in 2–3 days.

What research says works

• Neoseiulus cucumeris: Use preventively, before populations and damage are high (UConn).
• Amblyseius swirskii: Use preventively, before populations are high (UConn).
• Neoseiulus californicus: Use preventively (UConn).
• Amblyseius andersoni: UMass names it for broad mites as well as russet and spider mites. It may need repeated releases.

From FGMN

• Neoseiulus cucumeris
  Release early, before damage is heavy
• Amblyseius swirskii
  Release early; warm humid rooms
• Amblyseius andersoni
  Broad and russet mites; may need repeats
• Amblyseius andersoni Slow-Release Prevention SachetsPrevention only
  Prevention only

Timing: one good source

Sources (2)

1. Broad Mites and Cyclamen Mites on Greenhouse Crops, UConn Extension IPM
2. Tomato Russet Mite, UMass Amherst Vegetable Program

Also called: tomato russet mite, hemp russet mite

What you'll see: Microscopic and spin no webbing. On tomato, bronzing or browning starts on the lower stem and moves up. Leaves curl, yellow or bronze and look glossy underneath, then wither. On hemp, leaf edges curl up and leaves look dull, russeted or speckled. A leaf-shake test does not work for these mites.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: A greenhouse and high-tunnel problem in warm, dry conditions.

Indoors and in greenhouses

A greenhouse and high-tunnel problem in warm, dry conditions. Tomato russet mite has no dormant stage, so it survives winter only on living plants in heated greenhouses and nurseries and is carried into spring plantings from there.

When it spikes:

• Hot, dry greenhouse conditions: any time of year
• Transplants from overwintering greenhouses

Check again in: 3-7 days. The life cycle takes about 7 days in warm, dry conditions (tomato russet mite), or 8–15 days for hemp russet mite.

What research says works

• Amblyseius andersoni: Prevents or controls low infestations in greenhouses and high tunnels. Repeat releases may be needed. Wait 48 h after a pesticide application before releasing.
• Neoseiulus californicus: Purdue lists it for hemp russet mite but notes that efficacy research is limited.

From FGMN

• Amblyseius andersoni
  For low infestations; repeat releases

Timing: one good source

Sources (2)

1. Management Strategies for Common Arthropod Pests of Greenhouse Hemp in Indiana (E-275), Purdue Extension
2. Tomato Russet Mite, UMass Amherst Vegetable Program

Also called: sweetpotato whitefly, bemisia

What you'll see: Smaller and more yellow than greenhouse whitefly, and holds its wings tent-like. Pupae are yellow without filaments. Causes honeydew, sooty mold and yellowing. Can transmit viruses to tomato.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: Year-round in greenhouses.

Indoors and in greenhouses

Year-round in greenhouses. It likes heat, with adults most active above 80°F. It is a major pest of poinsettia in the fall production season. The Q-biotype resists many insecticides.

When it spikes:

• Incoming cuttings/poinsettias: any time of year

Check again in: 7 days. Eggs hatch in about 7 days at 65–75°F, and egg to adult takes 14–40 days. Sticky cards are changed weekly.

What research says works

• Eretmocerus eremicus: Best at 77–84°F and inactive above 86°F. More pesticide-tolerant than Encarsia.
• Eretmocerus mundus: Targets B-biotype only. Works over a wider temperature range than E. eremicus. Keep out of direct sun.
• Amblyseius swirskii: Eats whitefly eggs and nymphs.

From FGMN

• Amblyseius swirskii
  Eats whitefly eggs and nymphs

Timing: one good source

Sources (1)

1. Whiteflies on Greenhouse Crops, UMass Amherst Greenhouse Crops & Floriculture

What you'll see: Stout, house-fly-shaped flies about 1/8 inch long with short legs and 5–6 pale spots on each dark wing. They are stronger fliers than fungus gnats. Look for them around algae, puddles and wet benches. Larvae have no black head. Their fecal specks on leaves are mostly cosmetic.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: A greenhouse and indoor plant room pest wherever surfaces stay wet with algae.

Indoors and in greenhouses

A greenhouse and indoor plant room pest wherever surfaces stay wet with algae. Not strongly seasonal indoors. They build up fastest in warm conditions and in overwatered, poorly drained setups.

When it spikes:

• Standing water/algae from overwatering: any time of year

Check again in: 7 days. Egg to adult takes as little as 8 days at 78°F, or 14 days at 68°F.

What research says works

• Dalotia coriaria (rove beetle): A generalist that eats shore fly eggs and larvae. Release in the evening. Best used preventively along with drying out surfaces and controlling algae.
• Steinernema nematodes: UConn reports insufficient control because shore flies breed in semi-aquatic sites. Some growers use repeated high rates of S. carpocapsae.

From FGMN

• Dalotia coriaria - Rove Beetle
  Eats shore fly eggs and larvae; dry out wet surfaces too

Timing: one good source

Sources (1)

1. Managing Shore Flies in the Greenhouse, UConn Extension IPM

What you'll see: A white, powdery or waxy coating on the root ball that looks like root mealybug, so check with a hand lens. Plants are stunted, wilt in midday heat, or look nutrient-deficient.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: Present in greenhouses year-round.

Indoors and in greenhouses

Present in greenhouses year-round. Development is much faster in warm soil, so populations rise quickly in late spring and summer. Crawlers move between pots through drainage holes, water, reused pots, stock plants and weeds under benches.

When it spikes:

• Warming soil in late spring/summer

Check again in: 14 days. No sourced development time. A University of Maryland trial assessed treatments at 14 and 28 days.

What research says works

• Beauveria bassiana (fungus): Significantly reduced rice root aphid at 28 days (not 14) in a 2020 University of Maryland greenhouse trial.
• Soil predators (rove beetles, predatory mites): Observed active in root zones in the University of Maryland trial. Ants tending the aphids may need control for biocontrol to work. No efficacy data.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: rough estimate

Sources (2)

1. Critters Down Under: Root Aphids, Premier Tech Horticulture (industry technical article; not extension)
2. Evaluating New Control Materials for Root Aphids (Gill et al. 2020 poster), University of Maryland Extension

Also called: white jumping bugs in soil, snow fleas

What you'll see: Tiny (1/16–1/8 inch) wingless white, gray or dark specks that jump when the soil is watered or disturbed. Harmless, and they feed on fungi and decaying matter.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: Active year-round wherever soil stays damp.

Indoors and in greenhouses

Active year-round wherever soil stays damp. Large numbers in pots point to overwatering, especially in peat-rich mixes.

When it spikes:

• Overwatering: any time of year

Check again in: 7-14 days. Recheck after letting the soil dry. No development time is sourced.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: well documented

Sources (1)

1. Springtails, University of Minnesota Extension

Also called: european pepper moth

What you'll see: Chewed leaves and flowers with droppings (frass), rolled leaves tied with silk, and bored stems or buds. European pepper moth causes webbing at the soil line and stem-base collapse that looks like root rot.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: Caterpillars overwinter outdoors, and moths fly into greenhouses in summer and fall through doors and vents, drawn by lights at night.

Indoors and in greenhouses

Caterpillars overwinter outdoors, and moths fly into greenhouses in summer and fall through doors and vents, drawn by lights at night. Scout near openings, weedy areas and vegetable fields. European pepper moth rises in late summer.

When it spikes:

• Moths fly in through vents and doors: in zone 6, about late Jun to late Oct

Check again in: 7 days. No sourced development time. Bt breaks down under UV and must be reapplied (UConn).

What research says works

• Bacillus thuringiensis kurstaki (Bt): Needs thorough coverage and works best on young larvae. Reapply because UV and watering remove it.
• Trichogramma (egg parasitoid): Attacks only moth eggs, so timing is critical. Its cycle takes about 7–10 days. Protect it from ants.

From FGMN

We don't sell a biological control for this one. The options above are what the research supports.

Timing: one good source

Sources (1)

1. Managing Caterpillar Pests, UConn Extension IPM

Also called: mold mites, grain mites in isopod cultures

What you'll see: Masses of near-invisible mites that make stored material seem to 'move', and a tan 'mite dust' on surfaces near the food. Infested products include flour, grain, pet food, moldy hay and other stored feed. Handlers can get skin irritation.

Where it lives: Indoors and in greenhouses anywhere.

In short: Indoors: Tied to moisture rather than season.

Indoors and in greenhouses

Tied to moisture rather than season. Infestations follow damp, warm, humid storage and mold. Grain mites thrive at about 14% moisture content and become a serious problem at about 15–18%. In lab studies, warmer (20°C) and more humid (80% RH) conditions sped development and egg-laying.

When it spikes:

• Damp/humid storage of feed or substrate: any time of year

Check again in: 7 days. Bohart advises freezing suspect food for 1 week. No sourced development time.

What research says works

• Cheyletus eruditus (predatory mite): Used routinely in Czech grain stores against Acarus siro. Worked on oilseeds only when infestations started at about 50 mites/kg or fewer, so it should be applied preventively.

From FGMN

• Amblyseius swirskii
  Any Amblyseius predatory mite will take grain mites (FGMN house note)
• Amblyseius andersoni
  Another Amblyseius option (FGMN house note)

The predatory-mite pick comes from the FGMN team; extension sources reviewed here only cover a different predatory mite in grain stores.

Timing: rough estimate

Sources (4)

1. The Bionomics of Acarus siro L. on Oilseeds (Fejt & Zdarkova 2001, Plant Protection Science 37:111-114), Plant Protection Science (peer-reviewed)
2. Mites in Stored Foods, Washington State University PestSense
3. Grain Mite Infestation: Prevention and Control (GQ-13), Purdue University Cooperative Extension Service
4. Mold Mites (Tyrophagus), Information Note 39, UC Davis Bohart Museum of Entomology