PFamily APHELOCHEIRIDAE Fieber, 1851
The family is closely related to Naucoridae and often included in it as a subfamily. It contains only one genus, Aphelocheirus, with about 60 species from all parts of the Old World. Members of the genus are predators living in the benthos of streams and lakes, at depths up to 10 m. They have a plastron respiration, which allows them to live submerged during all their life. The common European species, Aphelocheirus aestivalis, feeds on the larvae of chironomids and trichopterans, and on molluscs. Eggs are laid on submerged objects and all stages overwinter. Development takes two years with copulation in the third year. Some species are known only in the macropterous form, others only as brachypters, and some exhibit wing polymorphism. In A. aestivalis it was shown that development of wings increased in stagnant water. Collecting of Aphelocheirus requires some experience. D.A. Polhemus & J.T. Polhemus (1989) recommend "to disturb the substrate while holding a net just downstream, so that the dislodged insects are carried into it by the current". Sometimes these insects are collected by hydrobiologists studying the benthic fauna and by ichthyologists studying the feeding of fishes. Macropterous specimens are sometimes collected at light.
Palaearctic catalogue: Kanyukova, 1995b. Revisions: Kanyukova, 1974 (species of the former Soviet Union); D.A. Polhemus & J.T. Polhemus, 1989 (Oriental fauna, checklist of species of the World fauna); J.T. Polhemus, 1989 (corrections and additions to D.A. Polhemus & J.T. Polhemus, 1989); Nieser & Millán, 1989 (key to W Palaearctic species). Phylogenetic relationships: Hoberlandt & Štys, 1979; Rieger, 1976.