What is this?
Location: Boulder, CO — Rocky Mountain foothills
June 30, 2011 10:38 pm
I ran across this insect while hiking in the hills around Boulder, CO. It’s about the size of my insect finger, and it flies as well. Otherwise, the picture should give you all the details you need.
Signature: IngridM

Giant Robber Fly

Hi IngridM,
This is one of the Giant Robber Flies in the genus
Promachus.  The species that are pictured on BugGuide all look quite similar and we do not feel confident taking the identification to the species level.

Location: Colorado

4 Responses to Giant Robber Fly

  1. P McClure says:

    just wanted to say this website answered my question. I recently photographed that same Giant Robber Fly in Pasadena, Texas on a bayou. It’s really ominous looking. Thanks!

  2. Becky Lipka says:

    Now I feel terrible, there was one in my bathroom and I killed it, it sounds like a good bug – I was thinking it was a horsefly and it would bite me while I was showering. Good to know what it really is because I’ve seen them in my garden a few times recently.

  3. Tioni says:

    Is it common to find the Giant Robber Fly in Missouri? I found a dead one in my truck.

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