Hoverfly

How to recognise it

The adult is a wasp-mimic that hovers motionless in mid-air then darts sideways - but it has two wings not four, huge eyes, and no sting. The larva is the predator: a small legless translucent green or cream maggot, often barely visible, sliding among aphid colonies.

Mistaken for

The adult is constantly mistaken for a wasp and swatted. The larva looks like a slug or a scrap of jelly and gets wiped off with the aphids it is eating.

What it eats

Aphids, Thrips, Red spider mite, Whitefly

How to attract it

The adults live on nectar and pollen and can only reach flat, shallow flowers. Umbellifers are the key: let coriander, dill, fennel, carrot and parsley run to flower. Phacelia and alyssum are magnets.

Plants that help

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

Lifecycle

The female lays eggs directly inside an aphid colony, so her young hatch surrounded by food. Several generations a year.

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

The thing people get wrong

One hoverfly larva eats roughly 400 aphids before it pupates. That is the single most useful number in organic gardening - and the reason a strip of flowering coriander beside the beans is worth more than a bottle of anything.