They are also popular with gardeners because they have an insatiable appetite for aphids and other small, destructive insects like scale insects. Both the adult and the grub devour these pests and the adult can eat as many as fifty a day. Because they have a nasty taste (from oil in their leg joints) they are not eaten by birds and so their numbers can build up in good years. However sometimes the aphids are protected by ants, which shepherd the aphid to the best places on the plants: they are rewarded by a secretion from the aphid called honeydew. Ants will gang up against the ladybirds and throw them off the plant. Even the aphids fight back: the larger adults apparently have a good kick!

In late autumn the adults go into hibernation; large numbers usually congregate in a crevice or under bark, although sometimes they are found in garages and sheds. In spring they lay their eggs on an aphid-infested plant and they hatch out about a week later. About six weeks afterwards they pupate for another week.