Picture I took – I swear on a stack of bug books
Location: Scott Lane, Sandown, NH
August 17, 2011 1:43 pm
Good afternoon
I know this is a 3 spot horse fly but thought other people might enjoy seeing it as well.
Signature: Bev Manning

Horse Fly

Hi Bev,
We looked on BugGuide for photos of a Three Spot Horse Fly, and we could not find anything with that common name, however, it is logical that
Tabanus trimaculatus could have that common name, as indicated in this BugGuide posting.  It is difficult to tell from your photo if your fly matches the pinned specimen on World Field Guide.  In a more practical vein, most people who encounter Horse Flies might be more concerned if the fly was a male or female since only the females are blood sucking biters.  Males feed on nectar, though we have read that females will also feed on nectar.  The eyes are the best way to quickly distinguish males from females, but alas, your lateral view does not illustrate the spacing between the eyes.  Your Horse Flies presence on a blossom would make us speculate that it is more likely a male than a female, but we cannot be certain.

Three Spot Horse Fly

Closest I got to the top of this fly.  Thanks very much for the reply
Beverly Manning

Hi again Beverly,
We can’t really disagree about this being
Tabanus trimaculatus, and this new view shows clearly she is a female because the space between the eyes is evident.

Yay – thank you.  Your time is very much appreciated.
Bev Manning


Location: New Hampshire

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