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

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The family occurs predominantly in the Australasian and Neotropical regions, although a few species are found in the Oriental, Nearctic and Palaearctic regions. Until recently this group was regarded as a subfamily within the family Rhyacophilidae. There are about 40 genera with approximately 150 species, placed in two subfamilies-Apsilochoreminae and Hydrobiosinae. Both subfamilies, with 14 genera and 57 species, are known from Australia.


Adults medium-sized, with wing span 10-30 mm, wings dark brown to black, often mottled; males usually with small areas of modified setae. Ocelli present. Maxillary palps 5-segmented in both sexes, segments 1 and 2 cylindrical, shorter than others, terminal segment simple; antennae as long as or slightly shorter than fore wing. Mesoscutum and scutellum without setal warts. Wings elongate, oval, venation complete, often differing in sexes; fore wings with hyaline line along M and hyaline areas around cross-veins r-m, m-cu and at arculus; vestiture in some genera evenly pubescent, arranged along veins, or with tufts of thickened upright hairs on veins; discoidal cell closed or open in fore wing, open in hind wing. Lateral filament to S5 in male often present; prominent ventromesal projection generally on abdominal segments 6, 7 or 8. Female abdomen in some genera terminates in slender ovipositor. Tibial spurs 1:4:4 or 2:4:4.

Larvae of Hydrobiosidae are free living, prognathous and usually inhabit mainly cool, fast-flowing mountain streams; a few are adapted to slow-flowing waters or even tolerate stagnant pools. They are predatory, mainly on other aquatic insects. The body is smooth with few, scattered, bristle-like hairs, colour varying from pale creamy white to greenish, only head and pronotum sclerotised. Fore legs modified; usually chelate or subchelate with tibia and tarsus reduced and claw closing against distal projection of femur. Abdominal gills absent; anal prolegs long and stout, apical segment sclerotised, claws simple. Larva constructs crude pupal chamber of small stones; pupa enclosed within amber-coloured, silken cocoon.