Flies in the Asilidae family are known as robber flies and are a diverse group of top predatory insects. There are close to a thousand species in the United States north of Mexico but an impressive number of these are concentrated in the west. Eastern states tend to have between 100 and 150 species or so depending on the exact location. The working list I have for Arkansas robber flies is here. The linked AR map list is here Main links for other state lists here.

Recently the ranges and diversity have been studied in cooperation with the University of Arkansas at Fayetteville. The museum website link is here. Thanks to Dr. Jeff Barnes for his assistance with this. He was the scientist, we have been the boobs with nets. Norm Lavers worked on this group of insects in Arkansas from the summer of 2003 to the 2010s. There are still no field guides; no simple texts. There is a new beautiful book for the SW sector by Rick Rogers just just out in 2019. I am indebted to Rob Cannings for sending me the original catalog of robber flies and the keys to the genera of the US. Even if it did put him on my wife's most wanted list.

Photos here are associated with the collection and local studies. The AR summary paper in pdf now published in 2007 is here pdf (have to select download button). The Atomosia paper is here (now requires login). And the Ceraturgus paper is here. Diogmites article is here. And the recent Stichopogon paper is here (now requires download of poster with map and images). Most of the shots here are of live individuals. Some specimen shots are included for comparison and for education. These photo collections will be updated yearly as we learn and locate more of these animals.

Key to the Genera of eastern North America

(Note that the updated Genera key is now figure rich and about 3 megabytes of information, so it is slower to completely download. Over a phone line it may require up to 10 or 15 minutes total.)

Also a Michigan paper from 1975 with keys online in pdf.

For now the pictures at the links below are divided into Efferia, Machimus, Laphriinae, Dasypogoninae, the large Promachus & Proctacanthus, the distinctive Leptogastrinae, the diverse Stenopogoninae and the Other robbers (everything else).

This arrangement is an artificial separation of convenience for now. (Note that experts still fight over the Efferia split into Nerax, Pogoniefferia and Albibarbefferia.) As with the butterfly and dragonfly pages more than one shot may appear on some pages. Scroll for more information. Update notices will appear on the web update page. Link to the Costa Rican page is here.

Efferia         Machimus

Laphriinae     Dasypogoninae

Promachus & Proctacanthus


Stenopogoninae    Other robbers

Robber Links