Dasypogon diadema - a robberfly

To identify flies to family level use a simple wing venation key such as A Key to the Families of British Diptera, an AIDGAP by D. Unwin, published by the FSC and available as a free download (scroll down to the titles list) or a more detailed key which includes many physical characters such as The European Families of the Diptera by P. Oosterbroek. The expert dipterists on the DipteraInfo forum are also very happy to identify, often to species level, from good photographs.

Scientific Name: Dasypogon diadema (Asilidae).

English Name: none, a robberfly.

French Name: L'Asile diademe.

5 Key Characters:

• large, bristly fly with a beard and stabbing proboscis.
• prominent hooked claw on the end of the front tibias.
• females are black with a white beard, white spots on the sides of the abdomen and an orangey red patch in the middle of the top of the abdomen.
• males are all black, including the wings (although they may have white faces and beards).
• legs may be black or orangey red.

Lookalikes: Molobratia teutonis, which always has yellowy orange antennae. Other Asilidae robberflies look superficially like this species, but are marked differently, and/or are more hairy.

Habitat: They require sandy places to lay their eggs into. The eggs are laid in groups of 2-6 encased in a cocoon covered in sand. The larvae are predators of soil dwelling beetle and bee larvae, the adults are predators of bees and wasps. Warmth loving.

Flight Period: June-July-August.

Status: Very common, but localised ie only found in suitable habitat.

References and Further Reading:
Notes on the biology of Dasypogon diadema (Diptera: Asilidae) by Fritz Geller-Grimm, a fascinating study of the species on an military base in Germany. Fritz Geller-Grimm is a world expert on Asilidae Robberflies.

Photographed by Loire Valley Nature:
All photos enlarge in a new window if you click on them. Row 1 female by a track in the Foret de Preuilly, June. Row 2 - 3 male by a track in the Foret de Preuilly, June.