The Life Cycle of Atrichops crassipes Meigen, 1820 (Diptera: Athericidae) at the Lower Schierenseebrook, a Lake Outflow in the North German Lowland

Abstract

The merolimnic fly Atrichops crassipes (Diptera: Athericidae) has a biennial life cycle in Lower Schierenseebrook, a lake outflow in the North German Lowland. Instar analysis based on larval head capsule length and width reveals five instars. The growth rate of successive larval instars remains nearly constant around 1.4, thus following Brooks' rule. Larvae hatch in July and August; the first hibernation occurs mainly during the third instar. Larvae develop to the fourth instar by the next summer and hibernate a second time as fifth instars. The last larval instar leaves the water at the end of May and pupates in the soil. The appproximately two-months flight period of the imagines begins around the middle of June. Females lay their eggs on the undersides of leaves of littoral trees, from which the hatching larvae fall into the water.