Robber Fly

Subject: Modernist Bug
Location: Vail, AZ
July 4, 2013 11:28 am
This is the first of this kind I have noticed. Was photographed on the Arizona Trail near Three Bridges. Landed in front of me like a grasshopper.
Signature: Carl

Robber Fly
Robber Fly

Hi Carl,
This is a Robber Fly and your individual is one impressive looking predator.  We are not certain of the species, but it does resemble members on the genus
Polacantha pictured on BugGuide where the information provided states that Polacantha arctuata is found in Arizona.  All of the photos on BugGuide of the species are males and we cannot locate any photos of females.  We believe your Robber Fly is a female.  We cannot locate any other images of Polacantha arctuata on the internet.  Your individual appears to lack the striped abdomen found on Promachus sackeni which is pictured on BugGuide.  While we cannot be certain of the species, we can tell you that Robber Flies are very adept predators and they often take large winged prey in flight.  Many species feed on large bees and wasps.  Perhaps one of our readers will have better luck with a species identification.

Wow! Thank you!

Eric Eaton Responds to our request
Eric Fisher is the go-to person for robber flies.  I’m sorry, I don’t have his e-mail address in my contact file….
This one appears to be a male in the genus Proctacanthus, if I know anything at all (which is sometimes suspect with asilids!).

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