Chironomidae are common inhabitants of most aquatic habitats, and often dominate aquatic insect communities in both abundance and species richness. Species occur in all continents, including Antarctica, and most major oceanic islands that have been investigated. The family is divided into 11 subfamilies and 22 nominal tribes. Although individual species occur in a wide range of habitats from terrestrial to fully aquatic, a total of 339 genera and 4,147 species are unambiguously aquatic in their immature stages. Greatest species and generic richnesses occur in the Palaearctic Region and Nearctic Region, respectively, but this pattern may largely reflect historical patterns of past taxonomic research efforts.
- Historical processes