Code QT039999

Very small caddisflies (micro-caddis) which live in ponds, backwaters and areas of deep silt. The larvae are free-living until the fourth instar 4, when they build a purse-like, usually laterally-flattened case about 3.5mm long, either of very fine sand grains or else of silk. The case is attached to the substrate immediately prior to pupation.

The full grown larva is thin and of uniform width from the head to abdominal segment one or two, but the remaining segments are greatly expanded. Identification to family is thus easy for final instar larvae based on body form.

Early instar Hydroptilidae, which are minute and rarely collected, lack such abdominal development. They are not considered specifically in the key and may be hard to distinguish from other families. However, early instar hydroptilids can often be recognised by their tiny size, lack of a case and slender, somewhat spidery/sprawled appearance. Many also have long setae trailing from the end of the abdomen (see second illustration). Wells (1985) described early instars for some genera.

Hydroptilids are world-wide in distribution, with some 14 genera in Australia and over 100 species.

References:

Cartwright, D.I. and Dean, J.C. (1982) A key to the Victorian genera of free-living and retreat-making caddis-fly larvae (Insecta: Trichoptera). Memoirs of the National Museum of Victoria 43 : 1-13.

Dean, J.C., St Clair, R.M. and Cartwright, D.J. (1995) A key to late instar larvae of Australian Trichoptera families. In: Hawking, J.H. (ed.) Monitoring River Health initiative: Taxonomic Workshop Handbook. Murray-Darling Freshwater Research Centre, Victoria, Australia.

Neboiss, A. (1991) Trichoptera. pp. 787-816. In: CSIRO, Insects of Australia . Volume 2. Melbourne University Press, Carlton, Victoria.

Neboiss, A. (1992) Illustrated keys to the families and genera of Australian Trichoptera. 1. Adults. Australian Society for Limnology Special Publication 9. pp. 87.

Wells, A. (1985) Larvae and pupae of Australian Hydroptilidae (Trichoptera), with observations on general biology and relationships Australian Journal of Zoology Supplementary Series 113 : 1-69.