Full-text - Norsk entomologisk forening

Species of the genus Helophilus (Dipt.,Syrphidae) found on Jaeren, Rogaland.Tore hTielsenZoological Museum, University of BergenIIIn the Palearctic region, the genus Helofihilus is representedby 20 species of which 11 are known from Denmark and England.The Helofihilus genus is closely allied to the genus Eristalis,which contains a greater number of species, often known as"rattail flies". The Helofihilus species, however, are distinguishedfrom these by several characteristics, of which the following arethe most conspicuous: the Helofihilus species have a distinctyellow pattern, large areas of the abdomen usually being yellowand the thorax having along it the parallel yellow or greyishstripes typical of the genus. The femora of the hind legs are oftenthickened while the hind tibiae are somewhat flattened laterally.The eyes are hairless and separate (adjacent in the male andhairy in both sexes of Eristalis). The species of both genera arelarge, or fairly large.The larva is of the "rattail" type, and, like Eristalis lives submergedin stagnant water containing rotting organic matter.The "tail" serves accordingly as a breathing tube. In some ofthe species several generations probably develop yearly.The Syrphidae of Jaeren were investigated during the period1963-65. 917 specimens of Helofihilus were collected on thelocalities shown in Fig. 1, and a great number of observations onthe most common species were made.The following 7 species were found: Helofihilus trivittatusFabr., H. fiendulus L., H. hybridus Loew, H. affinis Wahlb., H.consirnilis Malm, H. lineatus Fabr. and H. lunulatus Meig.Of these H. fie~zdulus and H. affinis have previously beenrecorded from Norway (Soot-Ryen 1943). H. fiendulus is common,and usually abundantly found in many parts of the country.Only small numbers of the other speciks were caught, and asfar as is known, H. trivittatus, H. hybridus, H. consirnilis, H.lineatus and H. lunulatus have not been recorded before fromthe Norwegian fauna.