There are hundreds of thousands of plant-feeding species worldwide. One major entomology reference puts plant-feeding insects alone at at least 500,000 species. That does not include mites, plant-parasitic nematodes, snails, slugs or larger animals. It also does not mean 500,000 species are coming for your houseplants. [1]
A plant feeder becomes a pest when its activity conflicts with what we want from the plant. A caterpillar feeding on its native host may be part of a healthy ecosystem; the same feeding on a nursery crop can be a production problem. “Pest” is a job description we give it, not a branch of the family tree.
So there is no honest, fixed worldwide total called “all plant pests.” There is a very large biological cast, and a much smaller set likely to visit any particular plant. Your plant’s identity, your location and where it has been help narrow that set.
This guide maps 44 recognizable pest groups and feeding categories, including houseplant, greenhouse, garden and outdoor crop pests. It is a broad inventory of the major groups, not a census of every species. Some categories overlap: a leaf miner can also be a beetle larva. We separate them where doing so helps you recognize the problem. [6]
You do not need to memorize the list. Start with the clue you have, then use the look-alikes to avoid accusing the wrong guest.
Start with what you see
Choose the closest clue to reach the relevant part of the guide. These are places to start looking, not diagnoses; growing conditions and ordinary plant structures can imitate pest damage.
Browse by pest group
Mites and thrips · Aphids, scales and mealybugs · Outdoor sap feeders · Chewers · Miners and gall makers · Root and soil pests · Occasional feeders and the wider world · What if it is not a pest?
A leaf is evidence, not a confession
Some pests take pieces of leaf. Others empty cells while leaving the outline intact. Aphids reach the plant’s sugar-transporting tissue; miners eat inside the leaf itself. That is why searching only for holes misses entire groups. [2–4]
“How to tell it is not” needs a little care. A clearly identified fungus gnat is not a thrips. But finding one does not prove that the plant has no thrips. Likewise, no visible webbing does not rule out spider mites, and a clean sticky card does not clear the roots.
In the inventory, the second part of each entry gives an alternative explanation or a stronger check. Where a microscope or diagnostic lab is the useful next step, that is stated plainly. Guessing more confidently does not improve the identification.
The viewing notes below tell you how to begin inspecting each group. “Visible” means you may spot the animal or its signs without magnification; it does not promise a species identification. Concealed stages still need uncovering, and a hand lens can help even when the animal is easy to see.
Is anyone still eating?
A scar is a record, not a live broadcast. Photograph a marked leaf so you have something to compare at your next inspection. Look for additional injury and living pests, rather than asking the original mark to disappear.
The two later checks show alternative outcomes. An unchanged scar alone is not evidence of continued feeding. Additional injury gives you a reason to inspect again, but it still needs an explanation: pests, growing conditions and delayed appearance of earlier damage can complicate the picture. Compare the leaves and look for the animal. This is a practical monitoring illustration, not a test that clears a plant of pests. [7, 54]
The tiny surface feeders
The illustrations pair each animal with representative damage or feeding signs. They are enlarged independently, not shown at a shared scale. A plant can lose living tissue without losing a visible piece of leaf. These are the suspects when the surface changes before you find an obvious animal. Magnification matters here; color alone is a poor identification tool.
01 Spider mites
Hand lens · inspect mites, eggs and leaf undersides
Fine pale stippling, bronzing and sometimes fine webbing; inspect leaf undersides for mites, eggs and shed skins. A spider’s web alone is not evidence of spider mites. Lack of webbing does not exclude an early infestation. [7]
02 Flat mites
Magnification · microscopic confirmation may be needed
Bronzed, roughened or necrotic patches may appear on leaves and stems without webbing. Examine damaged areas and crevices under magnification. Edema and old physical injury can also look corky; the scar alone cannot confirm flat mites. [8]
03 Broad mites
Microscope · inspect concealed young growth
Distorted, hardened or bronzed young growth can be the first visible clue. The mites are too small for a reliable naked-eye check. Similar distortion can come from cyclamen mites, chemicals or other injury. Microscopic identification is more useful than comparing leaf curls. [9]
04 Cyclamen mites
Microscope · inspect buds and growing points
Look at tight growing points, buds and crumpled young leaves, especially on susceptible plants. Broad mites and non-pest growing-point injury can look similar. A clean view of an old, expanded leaf does not clear the concealed new growth. [10]
05 Rust, bud, blister and gall mites
Microscope · identify the mite, not just the gall
These eriophyid mites can produce russeting, unusual hairs, blisters, galls or damaged buds, depending on species and host. Not every gall or rusty patch is caused by mites. Match the host and symptom, then seek microscopic confirmation when management depends on it. [11]
06 Bulb mites
Magnification · inspect the bulb and the animal
Acarid bulb mites occur around bulbs and other underground tissues, often alongside wounds and decay. A pale mite in potting mix is not automatically a bulb pest. Identify the organism and inspect the tissue; decay and mites may be present together. [12]
07 Thrips
Visible insects · hand lens for identifying details
Slender insects, pale young stages, silvery or aged scars and dark fecal specks can occur on leaves, flowers and buds. A fungus gnat has a different body and wing shape. Sunburn or abrasion can scar a leaf too, so look for insects and fresh evidence. [13]
Small does not make them the same
Aphids tend toward a pear shape. Thrips are narrow and elongated. Fungus gnats have the long-legged outline of a tiny mosquito. Adult whiteflies carry broad, pale wings. These are useful first distinctions, not species-level identifications.
Sticky cards can help you find flying adults, but the insect on the card still needs identifying. Card color is not a verdict. A plant can also have more than one visitor.
The sticky and cottony crowd
Honeydew is a useful clue because it can land below the animal producing it. If a leaf is sticky, inspect the growth above it as well as the leaf itself. Several unrelated-looking pests share this habit. [3]
Aphids
Where you find aphids changes where you need to look next. Some gather on leaves and tender shoots, where the colony is relatively easy to spot. Others feed around the roots, where a leaf inspection can miss them. The next two entries are the aboveground and belowground versions of that problem. [14, 15]
08 Aphids on leaves and shoots
Visible colonies · hand lens for details
Soft-bodied colonies often gather on shoots, buds or leaf undersides; shed skins and honeydew may accompany them. White shed skins are not a separate white insect infestation. Look for living aphids among them. [14]
09 Aphids around the roots
Expose roots · hand lens for colonies
For root-feeding aphids, move the inspection below the surface. Check roots and the outside of the root ball for colonies, sometimes with wax. White wax can resemble root mealybugs or fungal growth. Identify the animal under magnification rather than diagnosing the white material. [15]
10 Mealybugs on leaves and stems
Visible colonies · inspect beneath the wax
Mealybugs are a different group of insects, despite the shared fondness for hiding places and honeydew. Their oval, wax-covered bodies shelter in leaf joints, sheaths and other protected spots; colonies may produce honeydew. Lint, mineral residue, woolly aphids and some beneficial larvae can look cottony. Find the body beneath the wax. [16]
11 Root mealybugs
Expose roots · hand lens for wax-covered insects
Root mealybugs take that waxy appearance underground. White wax around roots, the pot wall or drainage area deserves a closer look for insects. Perlite and fungal threads are not mealybugs. White material alone is insufficient; inspect the roots and confirm bodies. [17]
12 Soft scales
Visible covers or bumps · hand lens helps
Rounded or flattened insects can resemble attached bumps on stems and leaves; honeydew is a common clue. Lenticels, corking and ordinary plant structures can resemble scale. Examine a suspect bump closely instead of scraping every bump off the plant. [18]
13 Armored scales
Visible covers · hand lens to examine underneath
Look for small protective covers attached to foliage or stems, with an insect beneath. Unlike soft scales, armored scales do not produce honeydew. Its absence does not clear them; its presence may belong to another pest. [19]
14 Whiteflies
Visible flying adults · hand lens for immature stages
Tiny white-winged adults may rise when leaves are disturbed; immature stages remain on leaf undersides. Fungus gnats are not powder-white mothlike insects. Empty whitefly cases can remain after emergence, so check for living stages too. [20]
Beyond the usual houseplant suspects
The same feeding neighborhood extends into landscapes, orchards and field crops. Here, knowing the host becomes especially helpful. A white colony on a conifer and one on a philodendron need not have the same name.
15 Psyllids
Visible adults or signs · hand lens for nymphs
Small jumping adults and flattened nymphs may accompany sticky deposits, distorted growth or protective covers called lerps. Their covers can resemble scale; adults can resemble other tiny jumping insects. Compare both stages and the host plant. [21]
16 Adelgids
Visible wax or galls · hand lens for the insects
These conifer feeders can appear as white waxy patches; some cause characteristic galls. A cottony colony on a non-conifer points away from adelgids and toward another explanation, such as mealybugs or woolly aphids. [22]
17 Phylloxera
Magnification · match the insect and host
These tiny aphid relatives can affect particular hosts; oak leaf phylloxera, for example, cause discolored leaf spots. Do not transfer an identification between unrelated hosts just because both leaves have spots. Host identity and the insect are essential clues. [23]
18 Leafhoppers and planthoppers
Visible adults · hand lens for details
Small mobile sap feeders may jump away when disturbed; some cause stippling, scorching or transmit plant pathogens. Jumping alone is not diagnostic: psyllids and springtails also jump. Inspect the body and match it to the plant and feeding location. [24]
19 Treehoppers
Visible insects · inspect stems
Many adults have a pronounced, sometimes thornlike body profile and occur on stems; feeding or egg-laying can injure tissue. A real thorn is continuous plant tissue. Look for legs and an insect body before deciding an odd projection is part of the plant. [25]
20 Spittlebugs
Visible foam · inspect the nymph inside
A frothy mass on a stem often shelters a nymph feeding within it. Foam by itself is not the insect. Gently inspect the mass; many light infestations cause little meaningful damage. [26]
21 Cicadas
Visible adults or wounds · nymphs are underground
Root-feeding nymphs live below ground; females of some species can injure twigs while laying eggs. Twig dieback has many causes. Look for characteristic egg-laying wounds or identified cicadas rather than blaming every dead tip on them. [27]
Some bugs puncture instead of sipping sugar
22 Lace bugs
Hand lens · inspect leaf undersides
Lace bugs are not lacewings. Lace bugs feed on plants; the beneficial lacewing larvae released for pest control eat aphids and other small pests—including lace bugs. If you bought lacewing eggs or larvae, you bought the predator, not the plant eater. Similar names. Very different dinner plans. [28, 57]
Pale stippling or bleaching above a leaf can accompany dark droppings and insects below; adults have delicate, lace-like wing surfaces. Spider mites can also stipple leaves. Finding lace bugs below the injured area separates the suspects more reliably than the pale surface alone. [28]
23 Plant bugs, stink bugs and relatives
Visible insects · closer identification may be needed
Plant-feeding members can puncture buds, fruit, seeds and shoots, causing distorted growth or localized injury. Some similar true bugs are predators. Identify the insect; a shield-shaped outline or puncture mark is not enough to label it harmful. [29]
That is the advantage of learning the feeding pattern: it tells you where to move your attention. It does not require you to announce a species name before you have found the animal.
When actual pieces are missing
Visible chewing takes us into a different part of the guest list. The shape of a bite helps, but many animals can make a ragged hole. Inspect at the time the damage is happening; a nighttime feeder may be absent from your lunchtime inspection.
24 Caterpillars
Visible larvae · inspect legs closely
Moth and butterfly larvae chew foliage, buds and other tissues; some tie or roll leaves with silk. Sawfly larvae can look very similar. Count the fleshy abdominal prolegs when visible; typical caterpillars have five pairs or fewer. [30]
25 Sawfly larvae
Visible larvae · inspect legs closely
These wasp relatives can strip or skeletonize foliage and often resemble caterpillars. Typical exposed, caterpillar-like sawfly larvae have six or more pairs of abdominal prolegs. This separates many from caterpillars, though unusual forms need closer identification. [31]
26 Leaf-feeding beetles
Visible adults or larvae · hand lens helps with small species
Adults or larvae may chew holes or skeletonize leaves; flea beetles often leave small shot holes. A beetle on a leaf may be a predator. Find feeding evidence and identify it; holes alone do not establish which beetle made them. [32]
27 Weevils
Visible adults · inspect roots for concealed larvae
Adult snout beetles may notch leaf edges; larvae of some species feed on roots or other concealed tissues. Leaf notches do not identify the larva below ground. Many root-weevil larvae are legless; scarab grubs have legs near the head. [33]
28 Scarab beetles and white grubs
Visible beetles or grubs · inspect feeding location
Some adults chew leaves or flowers; root-feeding larvae are often pale, C-shaped grubs with legs near the head. Not every pale grub eats living roots. Species and feeding location matter; a grub in decomposing material is not automatically the cause of plant decline. [34]
29 Grasshoppers, locusts, crickets and katydids
Visible insects
Plant-feeding members chew leaves and other tissues; many have conspicuous jumping hind legs. Some relatives also eat insects. Confirm feeding on the affected plant rather than treating every jumping visitor as the culprit. [35]
A bite is not always a problem to solve
30 Stick and leaf insects
Visible insects · camouflage makes them easy to miss
These camouflaged leaf feeders can be easy to miss on outdoor plants despite their size. Their chewing resembles other damage. Find the animal among stems and foliage; resemblance to a twig is camouflage, not a diagnostic leaf symptom. [36]
31 Earwigs
Visible insects · check after dark
The pincers at the tail are a strong identification clue. Some chew tender growth, flowers or fruit, often at night. Earwigs also eat pests. Seeing one is not proof of plant feeding; observe the damage and its activity before deciding it needs managing. [37]
32 Slugs and snails
Visible animals or trails · check sheltered places
Irregular holes, rasped surfaces and slime trails can lead to a soft-bodied mollusk, often under pots or active after dark. A missing slime trail does not exclude them. Caterpillars and beetles can make similar holes; look for the animal. [38]
Leafcutting bees deserve a special mention. They take neat pieces of leaf for their nests and are useful pollinators. A few tidy cutouts usually call for a different response from active defoliation. The plant has donated building materials. [39]
The ones already inside
Sometimes you turn the leaf over and still find nothing because the animal is between its surfaces. Others move into stems, buds, seeds or fruit. “Miner” and “borer” describe a way of feeding, so these categories overlap insect families. [4]
33 Leaf miners
Visible mines · the larva may be concealed or gone
Winding trails or blotches inside a leaf can contain larvae and their waste; certain flies, moths, beetles and sawflies do this. A scratch sits on the surface. A mine is within it, but may already be empty. Hold the leaf toward light and check whether there is an occupant. [40]
34 Gall-making insects
Visible galls · the occupant may need expert identification
Certain wasps, flies, aphids and other insects induce localized plant growth that shelters their developing stages. Mites and pathogens can also cause swellings. The host and gall structure guide identification; a lump alone is not a treatment decision. [41]
Tunnels, fruit and roots
35 Stem, wood, crown and shoot borers
Visible signs · the larva is often concealed
Larvae from several insect groups feed within stems or woody tissues. Holes, expelled debris and localized dieback can justify a closer inspection. Old exit holes do not prove a current infestation. Breakage, decay and disease also cause dieback; identify the borer and whether it is still active. [42]
36 Fruit, seed and pod feeders
Inspect inside affected fruit, seeds or pods
Fruit-fly larvae, seed beetles, weevils and caterpillars can feed inside reproductive tissues. Small flies near overripe fruit are not all pests of sound fruit. Inspect the affected tissue and identify the insects; the location alone is not enough. [42]
Below the potting mix, the same investigation becomes less visible. A plant may look thirsty because its working roots have been damaged. A root feeder can even sever tissue beyond the portion it eats. But watering problems and root disease can produce the same complaint. [5]
![A small bite can disconnect a larger root branch. Pale tissue here is detached, not consumed. Conceptual comparison. [5]](https://cdn.shopify.com/s/files/1/0712/8275/3778/files/fgmn-pest-guide-c362f511.png?v=1791031567)
The underground inventory
Root aphids, root mealybugs, bulb mites, some weevil larvae and white grubs already appear above. They are joined by these groups. When foliage gives you no answer, inspect drainage holes and the outside of a manageable root ball before taking it apart.
37 Fungus gnats
Visible adults · hand lens for larvae
Adults are small, long-legged flies; larvae in damp growing media have pale bodies and dark head capsules and can damage roots, especially on vulnerable young plants. Adults do not chew leaves. Shore flies have a stockier outline and are associated with algae; leaf scarring needs its own investigation. [43]
38 Root and seed maggots
Expose affected roots or bulbs · inspect larvae
Legless fly larvae can tunnel into susceptible roots, bulbs or germinating seeds in crop and garden settings. Fungus gnat larvae and other soil larvae need separating from them. Inspect both larva and damaged tissue; a white worm in soil is not an identification. [44]
39 Wireworms
Visible larvae · inspect soil and damaged tissue
These click-beetle larvae have firm, slender bodies and legs near the head; they can damage seeds, roots and tubers. They differ from soft, legless root maggots. Find the larva associated with the damage rather than naming the pest from a hole in a tuber. [45]
40 Garden symphylans
Magnification · inspect the legs and body
Small, white, many-legged soil arthropods can damage fine roots and seedlings. They are not the same as predatory centipedes. Young stages can resemble springtails; inspect legs and body under magnification. [46]
41 Plant-parasitic nematodes
Microscope or diagnostic lab · symptoms alone are insufficient
Microscopic roundworms include root-knot, lesion, cyst, foliar and other plant-feeding groups. Some form root galls; many do not. Root swellings can have other causes, including legume nodules. Beneficial nematodes also exist. Diagnosis commonly needs a properly collected plant or soil sample and a lab. [47]
The occasional offenders
Some organisms mostly recycle dead material but can feed on vulnerable living tissue. This is where “I found it in the pot” and “it is damaging my plant” most need separating.
42 Springtails
Visible moving specks · magnification for identification
Most familiar pot-dwelling springtails feed on fungi and decaying material; some species can injure seedlings or other tender tissue. Jumping specks around damp mix are not automatically thrips. Identify them and establish fresh plant injury before calling their presence an infestation. [48]
43 Millipedes
Visible animals
Usually decomposers, they can sometimes feed on seedlings or soft plant tissues. Their many short legs and segmented bodies help identify them. Do not confuse them with predatory centipedes, or assume that one under a pot caused the damage above it. [49]
44 Pillbugs and sowbugs
Visible animals
These terrestrial crustaceans mostly eat decaying material but can injure seedlings or tender tissues in moist settings. They are not root aphids or insects. Finding them under a pot is common; observed feeding and fresh damage matter more than presence alone. [50]
And the list keeps going
Those 44 entries are a map, not the edge of the subject. There are additional specialized crop, forest, turf and regional pests, plus species that matter only on particular hosts. Termites, leafcutter ants and other groups can also damage living plants in some settings. An indoor collector’s familiar list is a very small slice of plant protection. [52, 53]
Widen “pest” beyond small plant-feeding animals and the inventory expands again: deer, rabbits, rodents and birds can browse, gnaw or damage crops; weeds compete with wanted plants; parasitic plants such as dodder draw resources from hosts; fungi, oomycetes, bacteria, viruses and other pathogens cause disease. Those need different identification routes, not a longer search for mites. [51]
This is also why the worldwide number cannot be made by adding the headings in a gardening article. Species, life stages and feeding categories are different ways of sorting the same world.
What if it is not a pest?
Before assigning a suspect, ask whether the mark belongs to the plant itself, its environment, or something living on it without eating it. This is not a consolation prize diagnosis. It is the part that keeps treatment from becoming another source of damage.
Corky bumps may be edema. Pale or brown patches may follow excessive light, cold, rubbing or chemical injury. Yellowing can reflect root conditions or nutrition. The distribution and history help: did it begin after a move, a spray or a watering change? These are leads to investigate, not visual shortcuts that prove a cause. [54, 55]
Normal structures deserve a check too. Lenticels, corking, root hairs, dried sheaths and naturally patterned tissue can all look suspicious when you first examine a plant closely. Compare the same structure on healthy growth, then look for an actual animal rather than trying to remove everything unfamiliar.
Predatory mites, lacewing larvae, many lady beetles and their larvae, spiders and parasitoids may be there because pests are present. They are not all shaped like our idea of a helpful insect. Identify the visitor before treating it; even color and speed are only clues. [56]
Then there are the bystanders: springtails, decomposer mites and shore flies may be taking advantage of moisture or decaying material. Some can signal a growing-condition issue without being the animal that scarred the leaf. Two things happening in the same pot do not have to be cause and effect.
You do not need the whole guest list
You need the plant, the place and a clue that leads somewhere. Photograph fresh damage and both leaf surfaces. Note whether it is spreading. If you find an organism, photograph it under useful magnification; if the problem appears below ground, include the roots. A local extension service or diagnostic lab can use that evidence when a home inspection reaches its limit.
The goal is not to attach a pest name to every blemish. It is to work out who is there, whether they are responsible, and whether the damage warrants action.
Not everyone standing near the buffet ate your plant.
Sources and further reading
The research papers below support the feeding biology; the entomology reference provides the scale of plant-feeding diversity. University identification guides supply the broader inventory and look-alikes. The organization and inspection sequence are our synthesis, not a published universal diagnostic key. The illustrations are simplified teaching examples.
Numbers refer to these linked sources. Entries are grouped for practical recognition and are not mutually exclusive taxonomic units.
1. Phytophagous Insects · Encyclopedia of Insects (2009)
2. Bensoussan et al. (2016) · Cellular pattern of spider mite feeding · Frontiers in Plant Science
3. Douglas (2006) · Phloem-sap feeding by animals · Journal of Experimental Botany
4. Sinclair & Hughes (2010) · Leaf miners: The hidden herbivores · Austral Ecology
5. Erb & Lu (2013) · Belowground herbivores and plant roots · Journal of Experimental Botany
6. UC IPM · Invertebrate pest directory
8. UF/IFAS · A False Spider Mite
11. UC IPM · Rust, bud, blister and gall mites
13. Maryland Extension · Thrips in Home Gardens
14. UC IPM · Aphids on leaves and shoots
15. UMass Extension · Aphids on Greenhouse Crops
16. UC IPM · Foliar-feeding mealybugs
17. UMass Extension · Greenhouse update, May 1, 2025
24. UC IPM · Leafhoppers and planthoppers
27. UC IPM · Cicadas
29. UC IPM · Plant bugs, stink bugs and relatives
31. Maryland Extension · Sawflies
32. UC IPM · Beetles
33. UC IPM · Weevils
34. UMN Extension · White grubs
35. UC IPM · Grasshoppers, locusts, crickets and katydids
36. UC IPM · Leafrollers and look-alike chewing damage
37. UC IPM · Earwigs
40. Maryland Extension · Leafminers on Vegetables
41. Peer-reviewed review · The Evolution of Endophagy in Herbivorous Insects (2020)
42. UC IPM · Garden and Small Farm pest groups
43. UMass Extension · Fungus Gnats and Shore Flies
44. UMN Extension · Cabbage and onion maggots
45. Maryland Extension · Wireworms and Maggots
46. UC IPM · Garden symphylans
47. UC IPM · Nematodes in ornamental nurseries
48. UMN Extension · Springtails
50. UC IPM · Pillbugs and sowbugs
51. UC IPM · What Is Integrated Pest Management?
52. Texas A&M · Texas Leafcutting Ant
53. FAO · Soil biodiversity and termites
54. Maryland Extension · Diagnose Indoor Plant Problems
55. Maryland Extension · Edema of Indoor Plants
56. UC IPM · Natural Enemies Gallery
57. UC IPM · Green Lacewings. Supplementary identification and feeding guidance; see also source 28 for lacewing predation on lace bugs.
