Field Notes

Most aphid advice treats aphids as one pest. The parasitoid wasps do not. One of them will sting a potato aphid and be unable to develop inside it, which looks exactly like a release that did nothing. Here is how to tell which one you have.

Aphid numbers do not behave like insect numbers. A female gives birth to live daughters without mating, and those daughters already contain their own daughters before they are born. Everything else about aphids follows from that one fact.

Predatory mites are farmed. Nematodes are farmed. Lacewings, the aphid wasps, the mealybug destroyer — all farmed. Ladybugs are vacuumed off a mountain. That one difference explains most of what is strange about them, including the passengers.

Ladybugs, lacewing larvae, Aphidius wasps and Aphidoletes midges are not four strengths of the same thing. Three of them arrive, work and are finished. One of them leaves a next generation inside the colony, which is the difference that decides most cases.

A week after a ladybug release most of the beetles are gone and something else is on the leaves: small, dark, spiky, moving with purpose. People spray them. They are the part of the release that cannot fly away, and they do most of the eating.

A light sprinkle of ladybugs over an infested plant is the standard advice and it is not close to the rate that has been shown to work. In the one peer-reviewed garden trial, single releases at the recommended rate did nothing measurable. Here is the number that did something.

Ladybugs and predatory mites can run in the same space without meaningfully interfering with each other — but they're not doing the same job, and one won't cover for the other. Here's when the combination makes sense and when it's just extra cost.

Green lacewing eggs are laid on silken stalks — an evolutionary solution to two problems at once. Here's the biology behind the structure, what happens inside the egg as it develops, and how to deploy them effectively against aphids, mealybugs, thrips, and more.

They do fly away, and not because your plant disappointed them. Most are gone inside 48 hours whether or not there are aphids left to eat. That is worth understanding before you decide whether it makes them worth buying.