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Many entomologists argue that there is no such thing as a rare insect (providing its habitat remains intact). It is just a matter of knowing how to find it.

Nothoasteia clausa.
Western Clawless Upside-down fly Image: D Britton
© Australian Museum

There are many species of insect which are represented in the Australian Museum collection by just a single specimen - which may be the only one ever collected.

A good example is the Western Clawless Upside-down fly, Nothoasteia clausa. This fly was known from just a single specimen collected in 1980. Despite exhaustive searching, no other specimens could be found. It seemed that the Western Clawless Upside-down fly was very rare indeed.

A grass tree
A grass tree, typical habitat of the Western Clawless Upside-down fly, Nothoastia clausa. Image: D Britton
© Australian Museum

In 2001, Dr Gerry Cassis and Dr Toby Schuh of the Australian Museum stumbled across several specimens hiding deep down in the crowns of grass trees. Now that the scientists know to look for the flies in grass trees, more collecting has shown that the species is actually very abundant - not rare at all.

Another species in the same genus, Nothoasteia platycephala, is still only known from a single specimen collected from Brisbane. We have yet to discover how to find more examples of this species.

Museum collections contain many such examples, and there is still a great deal of research to be done if we are to discover the true abundance of species.