Family HYDROPTILIDAE

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Family HYDROPTILIDAE

Compiler and date details

Arturs Neboiss, Department of Entomology, National Museum of Victoria, Abbotsford, Victoria; updated (2002) by Alice Wells, Australian Biological Resources Study, Canberra, Australia

Introduction

This is a large family, commonly known as the micro-caddis; they are the smallest (wing span 4–12 mm) of all Trichoptera.

The family is known from all faunal regions and there are about 90 genera and 7–800 species. It is known throughout Australia and represented by 14 genera and 139 species. Wells (1992a) compared the microcaddisfly faunas of SE Asian countries, New Guinea and Australia, noting the domination of the Australian fauna by species in the tribe Hydroptilini and apparent absence from Australia of the tribe Stactobiini, which is very diverse throughout SE Asia and New Guinea. two stactobiine species have now been described from north-eastern Queensland (Wells 1990; Cairns & Wells 2008).

The Australian hydroptilid fauna includes a preponderance of algal feeding species, their larvae feeding on diatomaceous growth on macrophytes or rocky substrates or on filamentous green algae. Pseudoxyethira willcairnsi feeds on and builds its cases of an aquatic moss (Cairns &b Wells 2008). While some Orthotrichia species share a dietary preferences for filamentous algae and diatoms, many Australian species have been found feeding on eggs of aquatic invertebrates. Species in the Orthotrichia aberrans group, however, are parasitic on other caddisfly pupae, either philopotamids or hydropsychids (Wells 1992b). Larvae of Australian hydroptilids can be identified to genus using the key provided by Wells (1997).

Diagnosis

Adult: ocelli either present or absent according to genus. Maxillary palpi 5-segmented in both sexes, the first two segments very short and the apical segment simple. The antennae are shorter than the forewing; shorter in females that in the males; basal segment shorter than head. Mesoscutum without setal warts, scutellum flat, triangular, pointed posteriorly, margins vertical. Wings elongate, slender, usually acute apically, densely covered with fine pubescence, hindwing fringe with very long hairs, longer than width of wing; wing venation reduced, interpretation of veins often very difficult.

Tibial spurs variable: 0–1: 2–3: 3–4.

Larva: the first four instars are small, slender and free living. In the fifth instar the abdomen becomes enlarged and a purse-shaped case is constructed. Heavily sclerotized plates are on all three thoracic nota; mid- and hind-legs often longer than forelegs; anal claws are small. Larval case is (usually) laterally, but sometimes dorso-ventrally, flattened; it is constructed of small sand grains, algae, other plant material or entirely of silk. Before pupation the larva attaches the case to the substrate.