Warm summers encourage the development of large populations of aphids, leading to high numbers of aphid predators such as ladybirds (in 2025, a swarm of ladybirds invaded Lord’s cricket ground and held up a test match between England and India!).
Although the most easily recognised species is the 7-spot ladybird (Coccinella 7-punctata) with its red-and- black spot colouration, the Harlequin, Harmonia axyridis, has a number of different colour variations. Known also as the Asian ladybird, it was introduced into Europe (and America) to control pests like aphids and scale insects.
After mating, the female lays batches of eggs on the underside of leaves near an aphid food source on which its developing larvae will feed; although it is suggested that a single beetle may eat over five thousand aphids in its lifetime, it may also feed on the eggs and larvae of other insects within the locality. Once fully grown, a larva attaches itself to the surface of the vegetation before forming a hard, pupal case in which it will metamorphose into the adult beetle. Warm weather may result in several generations in a year.
In the winter, the adults remain dormant, often in large congregations, in warm, sheltered locations – sometimes in houses and other suitable sites. When Harlequins (or any other ladybird species) are handled, or feel threatened by predators, their defence is to secrete haemolymph (the insect equivalent of blood) from their legs; this fluid is distasteful to predators, has an offensive smell, and may leave a yellow stain on hands and porous materials like walls, furniture and fabric.
