"Hanging Thief"  - Multiple Mating Pairs
aka "Prairie Robber Fly"
Diogmites angustipennis   (four photos)

hanging thief robber fly mating pair
My sister-in-law, Nicky, and I were checking out small patch of sunflowers at Promontory Point and had found
a few
insects but nothing too unusual when I heard a loud buzzing sound. I figured it must be a bumble bee but
then I caught a glimpse of
orange legs and knew we had us a "Hanging Thief" Robber Fly.  © Carol Davis 8-20-2017

hanging thief
We not only had one Thief, but a mating pair and, not only that, we had many pairs
and many singles sporting their orange legs and black boots. It had suddenly turned
into a Thief orgy.  The females are larger than the males but both have those beautiful
green eyes and they buzz like bumble bees when agitated.  © Carol Davis 8-20-2017

hanging thief at Promontory Point
When they sit, their head is quickly moving from side or side or up and down as they spot an
insect flying by or landing. They look like predatory machines.  © Carol Davis 8-20-2017

hanging thief
Some of them, like this single fly, were just awaiting their turn at the mating ritual. I found this whole
scenario spooky because in the ten minutes before that, there were no Thieves to be found. We just
happened to be there at the right time and in the right place. It was wonderful and we got lots of
 pictures. I had never seen more than one of these insects at a time anywhere.  It made me wonder
if they were in some kind of Thief migration.  I felt kind of privileged to be documenting
this strange gathering of Prairie Robber Flies.  © Carol Davis 8-20-2017

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