Malaise trap in dried creek bed. Image copyright: M. E. Irwin.

Collecting Stiletto-flies:

Stiletto-flies can be found in all habitat types, especially arid regions but are found in areas such as beaches, rainforests, desert hilltops, gibberplains and even suburban gardens. Therevids are not particularly easy to hand collect in any habitat. An understanding of therevid biology gives us insight into how to best collect them. Like many insects, adult therevids require water and being in dry environments means that they need to seek out the water. Consequently, to best collect therevids, one should be at the water source waiting for the therevids to come to you, especially if water is restricted to drying pools or rainwater seeps. It is here that we can often best observe live therevids drinking. A well-placed Malaise trap next to a drying pool along a stream bed is an excellent method of collecting adult therevids. Moreover, therevids use pathways through vegetation and will fly along drying stream beds to locate water. Placing Malaise traps along dry creek and river beds and pathways through forest vegetation will also yield therevids. A significant number of therevids can be collected in Malaise traps, but hand-netting is used extensively as well.

Male therevids also display various types of lekking behaviour. Male leks consist of small aggregations of individuals in an arena where they display and compete for females. If you can locate these sites, they are good places to collect and observe male therevids. Examples of lek sites include tops of sand dunes, hilltops, openings in the forest, and sides of smooth barked trees such as Eucalyptus sp.

Therevid larvae can be collected easily by sieving soil through one or more sieves to remove the soil and leaving behind the larva and larger soil debris. Larvae live in most types of sandy friable soils, but also leaf litter and sandy loam. Larvae are often associated with their prey, and will commonly be around the bases of vegetation, rotting tree trunks, etc.

Tending to a Malaise trap next to a shallow stream in Australia. Image copyright: CSIRO.