In Australia, the butterfly subfamily Nymphulinae was thought to have about 60 described species in 23 genera (Common 1990), but these figures have been re-evaluated and the latest checklist reports 47 described species in 16 genera (Shaffer et al. 1996). These species were all described over a period of 80 years, with Walker (1859) naming the first species and Turner (1937) contributing the most recent species description (Shaffer et al. 1996). Throughout this period many adults were described but an identification key was not produced.
Similarly, there are no keys to the Australian larvae for any of the families, genera or species of Lepidoptera and recognition of the subfamilies and some of their genera must be by sourcing information provided by Northern Hemisphere keys. Some of the Nymphulinae larvae can be easily recognised by their external filamentous aquatic gills, which are diagnostic of some species of this subfamily. Those without gills are more difficult to identify, but it has been possible to produce a key to separate the Pyralidae from the information provided by Solis (1999), Common (1990), Stehr
(1987), Yoshiyasu (1985a), Speidel (1984), Hasenfuss (1960) based mainly on just a few species from each family. Therefore, users should be aware that some difficulties may be experienced when using the key, especially as the larvae of some species may not entirely conform to the current concepts of the relevant group.
This Identification Guide is intended purely as an introduction to the aquatic Australian Lepidoptera, and provides preliminary keys to voucher species that have been collected during monitoring surveys (e.g. National River Health Program) and through the CRCFE taxonomic and ecological research into Nymphulinae. The guide provides three keys: (1) key to the aquatic families, (2) key to gill-bearing Nymphulinae larvae and (3) key to non-gill-bearing pyralid larvae. Some non-pyralid larvae commonly occur in stream samples and several examples have also been included and will be the basis for future keys to the semi-aquatic larvae.
The ecology of the Australian aquatic caterpillars is poorly known and limited knowledge has been reported by Nielsen and Common (1991), and Common (1990). However, much of the information from outside Australia (Stoops et al. 1998, Lange 1996, Yoshiyasu 1985a) is relevant and can be used, with caution, until Australian studies are published.
The adult nymphulines are more speciose in the north and east of Australia, with 24 species found in Queensland, 16 species from the Northern Territory and 15 species from New South Wales. The larvae are known for only a few of the species from each state, except for Victoria and South Australia which have been surveyed in more detail.