The Coccinellidae are a family of small beetles, ranging from 0.8 to 18 mm (0.0315 to 0.708 inches). They are commonly yellow, orange, or scarlet with small black spots on their wing covers, with black legs, heads and antennae. Such colour patterns vary greatly, however; for example, a minority of species, such as Vibidia duodecimguttata, a twelve-spotted species, have whitish spots on a brown background. Coccinellids are found worldwide, with over 5,000 species described.
Coccinellidae are known colloquially as ladybirds (in Britain, Ireland, the Commonwealth, and some parts of the southern United States), ladybugs (originating in North America) or lady cows, among other names. When they need to use a common name, entomologists in the United States widely prefer the names ladybird beetles or lady beetles as these insects are not true bugs.
The Coccinellidae are generally considered useful insects, because many species feed on aphids or scale insects, which are pests in gardens, agricultural fields, orchards, and similar places. Within the colonies of such plant-eating pests, they will lay hundreds of eggs, and when these hatch, the larvae will commence feeding immediately. However, some species do have unwelcome effects; among these, the most prominent are the subfamily Epilachninae, which are plant eaters. Usually, Epilachninae are only mild agricultural pests, eating the leaves of grain, potatoes, beans, and various other crops, but their numbers can increase explosively in years when their natural enemies, such as parasitoid wasps that attack their eggs, are few. In such situations, they can do major crop damage. They occur in practically all the major crop-producing regions of temperate and tropical countries.