Four Aphid Answers, Compared. Only One Multiplies.

Four products in our catalog are for aphids. Ladybugs, green lacewings, Aphidius wasps and Aphidoletes midges. They are not four strengths of the same idea.

One question separates them, and it is not how much each one eats. It is whether the thing you release reproduces inside the problem. Three of these arrive, work, and are finished. One of them turns the aphid colony into a wasp factory.

That difference decides most cases, so it is worth taking in order: what each one is, what it actually removes, and which problem it fits.

The question that splits them

A predator you release has a working life, and when it ends the predation ends with it. A ladybug larva eats aphids for about two weeks and then pupates. A lacewing larva does the same. An Aphidoletes larva does it for a few days and then drops off the plant to pupate in the soil. In each case, what you bought is a finite quantity of eating.

An Aphidius female does something structurally different. She lays a single egg inside an aphid. The larva develops in there, kills the aphid, and the aphid's skin dries into a crusty tan shell — a mummy — stuck to the leaf. Five to ten days later an adult wasp chews a round hole in it and flies out, and that wasp lays too.

So the count that matters for the wasp is not aphids per wasp. It is generations. That is why aphid problems that keep spreading are a parasitoid case. An aphid gives birth to live daughters that are already carrying daughters of their own, so anything that does not reproduce on your plant is racing something that does.

The four, side by side

Ladybugs

The cheapest predation per dollar in the category, and the least durable. An adult convergent lady beetle eats about a hundred aphids a day, which is a lot, for the day or two before it leaves — and it leaves whether or not aphids remain. Nobody has established why, and the measured fact is the useful one: prey on the plant does not hold them.

The durable half is the eggs. A beetle that lays before it goes leaves larvae that cannot fly and stay for about two weeks. The spiky grubs are where most of the eating actually happens.

Larvae are not automatically the better buy, though. A 2017 review of greenhouse ladybird releases found released larvae less effective per individual than released adults, with the gap closing for flightless strains. An adult is worth more because it can search, and worth less because it can leave.

Aphids are what a ladybug release treats. Other soft-bodied insects and insect eggs get taken opportunistically — a treat, not a treatment — so do not buy them to break a mealybug or scale problem. And the rate is the thing most people get wrong: the published figures are far above what most labels suggest.

Lacewing larvae

The most predation you can buy in a single body that stays put. One larva takes 300 to 400 aphids over about two weeks, across three molts, on the plant you put it on.

Two things to know before buying. First, the adult is a different animal. What emerges after the larva pupates feeds on honeydew, pollen and nectar and takes no pests at all, so a lacewing release is one wave of larvae unless you are keeping flowering plants nearby and getting lucky. Second, they cannibalize. Larvae will eat each other when prey runs short, which is why a lacewing release onto a thin colony can end with fewer predators and no aphids removed.

We sell them as eggs and as larvae, which are genuinely different purchases rather than two sizes of one. The eggs sit on the ends of silk stalks, and the stalks are there to stop the hatchlings eating their siblings.

Aphidius wasps

Small, dark, about the size of a fungus gnat, and the only thing on this list that compounds. A female inserts one egg per aphid, and about seven to ten days later the larva kills its host and the aphid dries into a mummy — crusty, puffy, smooth, brown to gold or tan, still glued to the leaf. Egg to adult is roughly two weeks in summer conditions. What emerges goes looking for more aphids.

How many she gets through depends on who you ask: UC IPM puts it at one egg in “about 100 aphid nymphs of any size,” while Kansas State puts a female at more than 300 eggs over four to five days. Either figure is a lot for an insect that lives about ten days, and the compounding matters more than the count.

Which species, and why

The trade sells colemani as the small-aphid wasp and ervi as the large-aphid wasp. What the sources actually say is a species preference, and the size shorthand is a summary of it:

Both are less active above 86°F, and ervi stops below about 46°F. They ship as mummies in a carrier, so what arrives is a container of parasitized aphid shells that wasps emerge from over the following days — which means an arrival that looks like nothing is an arrival that is working.

Aphidoletes midges

A gall midge whose larvae are aphid predators. Small orange larvae work through a colony — a minimum of seven aphids to complete development, up to eighty, and they kill more than they consume. The adults are nocturnal, rarely seen, and feed on honeydew rather than on pests.

Two requirements that are easy to miss and that decide whether it works. The larvae drop off the plant to pupate and burrow into the medium, so there has to be damp soil or moist rockwool underneath — a dry bench or a saucer breaks the cycle. And shortening daylength induces diapause, which is a real seasonal limit rather than a quirk: as late summer arrives, a release can simply go to sleep. Greenhouses get around it with supplemental lighting.

In greenhouse conditions the adults are most effective at roughly 68 to 79°F with high humidity.

Why growers buy two

The pairing commercial growers run against a spreading aphid problem is a predator plus a parasitoid: something that eats now, and something that breeds where the prey is.

And there is a precondition that outranks the choice entirely. A 2017 review of ladybird releases in greenhouses concludes that “ladybird encounters with aphid-tending or foraging ants must be reduced” before the predation potential is realized — in one of the studies it reviews, fire ants cut ladybird larval survival by 84 to 93 percent. Ants farm aphids for honeydew and defend them. If ants are running the colony, none of these four is the answer until that is dealt with.

The logic is that the two have complementary failures. The predator takes the visible colony fast and then runs out of individuals. The wasp starts slowly — the first mummies are a week away and the first emerged wasps two — but it finds the colonies you cannot see and keeps producing. Run them together and the predator covers the wasp's slow start while the wasp covers the predator's finite lifespan.

That is also the honest answer to “which one is strongest.” None of them. The question is what shape of problem you have, and if the answer is “it keeps appearing somewhere new,” no amount of predator is the fix.

When each one is the wrong pick

Common questions

Ladybugs or lacewings for aphids?

Ladybugs for a fast knock-down on a heavy visible colony, because an adult eats about a hundred aphids a day — but most leave within a day or two. Lacewing larvae for sustained work on a plant you can reach, because one larva takes 300 to 400 aphids over about two weeks and cannot fly away. If the colony is thin, lacewing larvae will cannibalize and ladybugs will disperse, and neither is a good buy.

What is better, Aphidius wasps or ladybugs?

They answer different problems. Ladybugs remove a large number of aphids immediately and then stop. Aphidius removes them slowly and leaves a next generation of wasps inside the colony, so it keeps going and finds colonies you have not spotted. For a single infested plant, ladybugs. For aphids that keep turning up on new plants, the wasp.

What are the little brown crusty aphids on my leaves?

If you released Aphidius, those are mummies and they are the product working. A parasitized aphid dries into a crusty, puffy, tan-to-gold shell that stays stuck to the leaf, and about five to ten days later an adult wasp cuts a round hole in it and flies out. Leave them alone and do not wipe them off.

Which Aphidius species do I need?

Colemani is chosen for green peach aphid and melon or cotton aphid, both small species. Ervi is chosen for potato aphid and foxglove aphid, both large. Matricariae parasitizes at least 40 species and is the sensible pick if you cannot identify what you have. Getting a photograph of the aphid before you order is worth the five minutes.

Can I release more than one of these at the same time?

A predator and a parasitoid together is the standard commercial pairing and they complement each other. Two generalist predators at once mostly compete, and a generalist beetle will occasionally eat something smaller that you also paid for. If you want both, stagger them rather than tipping everything out on one evening.

Do any of these prevent aphids?

Not really. All four are responses to a colony that exists — a beetle lays next to prey worth laying next to, a lacewing larva starves on a clean plant, a wasp needs aphids to lay in, and a midge needs a colony for its larvae. Releasing any of them onto clean plants gets you very little.

Why did my Aphidoletes do nothing?

Two usual reasons. The larvae have to drop off the plant into damp soil or moist medium to pupate, so a dry bench or a bare saucer ends the cycle after the first generation. And shortening daylength in late summer induces diapause, so a release can go dormant rather than fail.