The Robber Flies of Crowley's Ridge, Arkansas

An Illustrated Field Guide by Norman Lavers

Asilidae : Laphystiinae

Species of Crowley's Ridge

Previous Subfamily: Laphriinae

The Laphistiinae are generally very small to tiny flies. Only two species, both in the Genus Psilocurus, occur along Crowley's Ridge. The individual here is doing what Robber Flies almost never do, and that is, landing on flowers. It's probably just a coincidence, but it makes you wonder if it is pretending to be an innocent bee, waiting for some unsuspecting tinier insect to arrive.

Psilocurus birdi birdi

The first species is Psilocurus birdi, a small fly only a little larger than an Atomosia. You will find it, in mid-summer, either on the poison ivy leaves in woodland, or in tall grass in a field. The best mark is the plump-appearing bee-like banded abdomen.


These tame little flies often appear in a blackish form.


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Psilocurus nudiusculus

The other species is Psilocurus nudiusculus. It is even smaller, and is perhaps best identified by its habitat. I find it near water in bottomland woods on bare sand or silt with scattered grass or other low sparse vegetation. A very small robber landing on or near the ground on, say, a path next to a swamp or canal, will likely be this species. Depending on the light, the eyes often appear bright green.


The male of P. nudiusculus is smaller still, with a bit more marking on the abdomen. He often makes a hovering courtship flight before the female, rather like Atomosia puella.


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Next Subfamily: Stenopogoninae