Whirligig beetles

Code QC100000

Larvae elongate, parallel sided, length 6-25 mm when mature. Gyrinid larvae are easily distinguished from other Coleoptera by the presence of distinctive paired abdominal gills on segments 1-8, with two pairs present on the ninth segment. Two pairs of hooks are present on the 10th abdominal segment. Legs are 6 segmented with 2 claws, antenna four segmented and elongate. Mandibles prominent and with an internal perforation for sucking. Gyrinid larva superficially resemble the larvae of some Megaloptera (especially Corydalidae), however the four anal hooks arising from abdominal segment ten distinguish gyrinids; megalopterans either have 2 hooked anal prolegs (Corydalidae) or a single long median process arising from the ninth abdominal segment (Sialidae).

Gyrinids (suborder Adephaga) occur in both lentic and lotic habitats, adults swimming in the surface film and larvae crawling, fully submerged, along the bottom (benthos). Larvae are voracious predators of soft bodied worms and insect larvae. Pupation occurs in cocoons out of the water on emergent plants or the banks. Four genera, comprising around 25 species, occur throughout Australia, with Macrogyrus being most abundant and diverse. No genus is endemic, but most species are.

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) Gyrinidae (Adephaga) pp. 319-320. In: Stehr, F.W. (ed.) Immature Insects. Volume 2. Kendall/Hunt Publishing Company, Dubuque, Iowa.