Parasitic wasp (Aphidius)

How to recognise it

The wasp itself is 2-3 mm, black and harmless to people - you will rarely see it. What you WILL see is its result: aphid mummies. A parasitised aphid swells, turns papery tan or bronze, and stops moving, with a neat round exit hole once the wasp has left.

Mistaken for

Those bronze mummies look like dead diseased aphids, so people spray the colony to finish the job - killing the wasps developing inside. A mummy is not a dead pest, it is a live ally about to hatch.

What it eats

Aphids

How to attract it

Nectar from tiny open flowers - they cannot feed from deep blooms. Alyssum, phacelia and the umbellifers. Above all, do not spray broad-spectrum insecticide.

Plants that help

Phacelia, Coriander, Dill, Calendula, Fennel (herb)

Lifecycle

The female injects a single egg into a live aphid; the larva eats it from inside and pupates within the hollow skin. Ten to fourteen days per generation - faster than the aphids in cool weather.

Months: April, May, June, July, August, September, October

The thing people get wrong

When you see bronze papery mummies among the aphids, stop and do nothing. Each one releases a wasp that will parasitise dozens more. Spraying at that moment is the single most self-defeating thing you can do in a vegetable garden - you remove the control that was already winning.