Predacious diving beetles

Code QC090000

Larval body generally fusiform to ovate, but sometimes more elongate and parallel side, length 1.5 to over 70mm when mature. Dytiscid larvae posess elongate, slender, 4 segmented antenna, often with up to 5 additional accessory segments. Head and mandibles prominent, strongly exserted in dorsal view. Mandibles hollow or grooved for sucking body fluids of prey, unlike Noteridae. Legs of 6 segments including paired claws distinguish dytiscid larvae from hydrophilids, which have 5 segmented legs with one claw. Eighth segment often elongate and siphonate (bearing spiracles at apex). Urogomphi generally long and prominent, occasionally shorter and stubby. Gills absent in Australian forms, abdominal segments lacking hooks.

Dytiscidae (suborder Adephaga) live in a variety of lentic and lotic habitats but are most common in the littoral zone at the edges of lakes and ponds. Most larvae use their mandibular channels for injecting digestive enzymes into prey and sucking out the resultant fluids by means of a cibarial-pharangeal pump. Pupation occurs in damp soil out of, but still near, water. Around 185 species and 36 genera are recognised from Australia, occurring in all states, with greatest diversity occurring in the south-east.

References:

Lawrence, J.F. and Britton, E.B. (1991) Coleoptera. pp. 543-683. In: CSIRO, Insects of Australia. Volume 2. Melbourne University Press, Carlton, Victoria.

Spangler, P.J. (1991) Dytiscidae (Adephaga). pp. 315-319. In: Stehr, F.W. (ed.) Immature Insects. Volume 2. Kendall/Hunt Publishing Company, Dubuque, Iowa.

Williams, W.D. (1980) Australian Freshwater Life: The Invertebrates of Australian Inland Waters. The Macmillan Company of Australia, Melbourne.