Male Black Horse Fly, Tabanus atratus
Location: Columbia, Missouri
September 13, 2011 12:39 pm
Here’s a pic I thought you might like for your files. This marvelous beast of a fly was on a black truckbed liner, and very wary–got one shot. Found mid-June, mid-Missouri, at a small camp site in a rural area (farms around).
The color in this image was not edited in any way, FYI.
Thanks to your site, which I visit regularly (and link to, on my blog), I was able to positively identify it pretty easily. Thanks for all you do!
Signature: Lisa, aka ”Mycologista”

Black Horse Fly

Hi Lisa,
This is a positively gorgeous male Black Horse Fly and a gorgeous photograph as well.

Buzzing in the Brown eye Susan
Location: northeast Missouri (backyard)
August 18, 2011 1:30 pm
Hi! This creature was found hovering near Brown eye Susan’s on 8/17, at 7:53pm , heavy twilight. Actually there were 3 of them. They made a loud buzzing sound. They made no attempt to sting us, or get near us, they would hover in mid air and ”look” at us. My brain could only think a moth creature. In my moth guide the only one I could find resembling the not very clear pictures is a ”bagworm” moth. What do you think?
Signature: Jan

Female Horse Fly Hovering

Hi Jan,
Your photos of a hovering female Horse Fly are a wonderful addition to our site because they reveal the female of the family as more than a blood sucking fiend.  She also feeds from flowers.  You can tell she is a female by the space between her eyes.

Hovering Horse Fly

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

Unidentified black fly in Herndon, VA.
Location: Herndon (4 miles from Dulles Airport), Virginia
August 12, 2011 4:55 pm
Hi Bugman,
We found this very cool all-black fly in the backyard yesterday just before dusk (8pm ish EST).
The body is all black, no color or shimmer anywhere not even in the wings or eyes. 2 large compound eyes – black. 2 wings are solid black in color and non-transparent. They attach at the shoulders either side of a flat black plate behind the head and close in a very wide v-shape.
Frontal abdomen shows distinct horizontal bands, black and hairless.
Dorsal abdomen is covered in black hair. Abdomen has rounded end but no ovipositor or other abdominal structure that I can see.
6 regualar fly legs, black, (did I mentions he is all black?)and two short splayed antennae at very top of head originating between eyes.
Last thing, couldn’t identify mouth parts but he has a very large depending proboscis – also black. He is more than 1in in length with wings longer. In the pics he (she?) is inside a drinking glass with an adult hand holding it for scale. Hope that helps. I hope you don’t have any questions because we released him after the photoshoot but we would truly love to know what kind of beastie he is. (I have more pics if you need them.) Many thanks in advance.
Signature: Anna & Aoife

Black Horse Fly

Hi Anna and Aoife,
Our editorial staff spent considerable time during our formative years in nearby Reston.  This is a Black Horse Fly, Tabanus atratus, a species that depends upon an aquatic environment for the development of the larva, and the presence of livestock as a food source for the blood sucking female adults.  It is possible to tell the sexes apart by viewing the eyes, which alas, your photos do not provide the necessary details for that distinction.  The large eyes of the male are closer together, and they touch one another.  In the female, there is a space between the eyes.  See BugGuide for additional photos.

Mr Marlos – fabulous to get a reply from you, thank you.
Aoife is my 12yr old daughter who found and captured the fly.  She will be thrilled to receive your response.
So it’s a Black Horse Fly. It’s so big. I had no idea they could get that big.
As ex-Restonites you will know that there’s plenty of local aquatic environment to grow babies but not so much livestock any more. My dog regularly comes in with big bug bites on his hairless belly so perhaps we are doing our part for the species after all.
My apologies for the lack of eye-detail. It was coming on dusk and rather than hunt for the camera we took hasty shots with a cell phone. I cannot say for sure if the eyes were touching but we were happy to find the bug and even happier to know what it is. There are such marvellous creatures in your own back yard in this country. Long may they thrill us and thank you again for doing what you do.
Best regards from myself and my larvae.
Anna, Aoife, Jess & Sarah.