We have a lot of robber flies around the FWG, including these small ones found in the BYG. I haven't yet had time to try and key out which of the many, many small Asilids they are.
I just looked up Robber Flies on Wikipedia being curious as to why they are called Robber Flies. They apparently stab their victims, other insects, with their proboscis and inject them with saliva containing neurotoxic and proeolytic enzymes which paralyze the victim and digest the insides. The fly then sucks up the liquified meal through the proboscis. Pretty gruesome stuff! Especially if you are an insect . There are about 7100 species worldwide so I am not surprised that they are difficult to ID .
Claudia
