The life cycle and benefits of ladybirds in field crops

There are 53 species of ladybirds (Family: Coccinellidae) in the UK, of which five are important for controlling aphids on cereals, potatoes and sugar beet.

Eggs are easily recognisable: usually elongate, oval-shaped and laid end-up in batches. Their colour varies between species, ranging from light yellow to dark orange.

Larvae are brightly coloured and have a distinctive appearance. They are commonly seen feeding on aphids in crops.

Adults (1–10 mm long) are, typically, brightly coloured (yellow, orange or scarlet), usually with patterned (spots, bands or stripes) wing covers, domed bodies and short, club-shaped antennae.

The life cycle usually lasts about 1 year; occasionally there are two generations per year. Eggs are laid in spring to early summer, close to their larval prey.

Pupation occurs in mid-summer and adults emerge during mid-to-late summer. With sufficient food and warmth, larval development is faster and two generations per year are possible. They overwinter as adults in sheltered places, such as in leaf litter, grass tussocks, bark crevices and buildings. They emerge in spring and seek out mates.

Their most common food is aphids and scale insects, although a few species feed on fungi. The 24-spot species feeds on plants. Five species are considered important for the control of aphids on cereals, potatoes and sugar beet. Ladybirds are good flyers; however, adult dispersal is random and it is only when they settle on a plant that more systematic searching occurs, aided by olfactory cues.

Threatened by the invasion of the non-native Harlequin ladybird, which competes for food and consumes the larvae of native ladybirds.

Adults are attracted to simple, open flowers; for example, wild carrot, angelica and yarrow, where they feed on nectar and pollen. The use of broad-spectrum insecticide sprays should be avoided.