What Bug Is That? The guide to Australian insect families.

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Hygrobiids are relatively slow-moving, bottom-feeding predators, occurring in stagnant water. Adults swim using alternate leg movements, and periodically come to the surface for air, which is stored beneath the elytra. Adults stridulate using the abdominal apex and a file on the undersurface of each elytron. Both adults and larvae are predacious, and the European Hygrobia hermanni is known to feed on tubificid worms (Balfour-Browne 1922).


Stout and oval beetles with strongly protuberant eyes and relatively small hind coxae (not greatly enlarged like those of noterids, dytiscids and gyrinids). Metasternum with transverse suture; tibiae and tarsi with swimming hairs. Larvae broadly fusiform, with enlarged head and prothorax; mandibles falcate but not perforate; tibiae and tarsi with swimming hairs; paired gill tufts arising from coxal bases and S1--S3; apical abdominal segments reduced and modified; segment 8 with long and narrow median process; 9 with 2 long and narrow urogomphi, and 10 membranous; functional spiracles present in last instar only.


The family comprises five species of Hygrobia : one from western China, one from Europe and North Africa, and three from Australia. Two of the Australian species occur in the south-eastern part of the continent, while a third is known from N.T. and Cape York (Britton 1981).