The following people must be thanked for their contributions to this key.
Ben Gunn (CSIRO Entomology), for his contribution of taxa and character
images. David Cartwright, John Dean
(Victorian Environmental Protection Authority), Jean Jackson (Inland Fisheries
Commission, Tasmania), Rosalind St. Clair (Victorian Environmental Protection
Authority), Gunther Theischinger (NSW Environmental Protection Authority) and
Alice Wells (Environment Australia), for the loan of many of the specimens used
Trichoptera (Caddisflies) are small, moth-like insects with winged adults
and aquatic larvae. The larvae
differ from those of Lepidoptera (moths and butterflies) in having only one pair
of abdominal prolegs (on segment 10) rather than five (on 3, 4, 5, 6 and 10)
Many trichopteran larvae build moveable cases out of sticks, leaves, reed
stems or sand grains, while the free-living species generally construct silken
nets or retreats underwater. The
cases alone often are sufficient to identify specimens to the family level.
Cases often, however, become damaged or are abandoned on handling and
many specimens obtained from bulk collecting methods cannot be directly
associated with their case. Examination
of the animal, or at least the head, is frequently necessary for family level
identification, and a full examination generally is necessary for identification
to genus and species.
This Key to Trichopteran larvae includes characters relating to case
construction but mainly addresses the anatomy of the animal itself, which
requires careful withdrawal of the animal from the case.
The key covers 24 of the 25 families which occur in Australia.
The larvae of Stenopsychidae is unknown but might resemble
Polycentropodidae, to which family the adults of Australian species were
previously referred. The key also
covers the single family of Lepidoptera: Pyralidae, in which the larvae of some
species are aquatic.
Note that this key works well for late instars, but should be used with
caution for early instars (for example, gills may not be developed in some very
young individuals). A particular
problem applies to the Hydroptilidae (micro-caddis), which are keyed largely on
the basis of an expanded abdomen. This
is characteristic of final instar larvae only.
Early instar Hydroptilidae are minute, free-living and rarely collected.
They are not considered specifically in the key, but 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 in the Hydroptilidae taxon notes).
Wells (1985) described early instars for some genera.
The most up-to-date key to the families comes from:
Dean, J.C. and Cartwright, D.I. (1991) Keys to families of Australian
Trichoptera Larvae. Taxonomy Workshop, Murray-Darling Freshwater Research
Centre, Victoria, Australia.
This work complements and expands the key presented by John Dean in:
Neboiss, A. (1991) Trichoptera. pp. 787-816. In: CSIRO, Insects of Australia. Melbourne University
Early instars of some hydroptilid genera are described and illustrated
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.