Currently viewing the category: "Horse Flies and Deer Flies"
What's That Bug? does not endorse extermination

Subject:  Beautiful biting fly (with bonus Karner Blue)
Geographic location of the bug:  Albany Pine Bush, Albany, NY
Date: 07/07/2020
Time: 12:33 AM EDT
Your letter to the bugman:  Dear Bugman,
Susan B. here with another dispatch from the Albany Pine Bush! I was having a nice raspberry-picking expedition along the trail when a rather beautiful fly came along and landed on my finger. I was so enchanted by its incredible eyes that I failed to notice it had stabbed its proboscis right into my flesh! I shooed it away, and I still have a sore spot where it bit me. Any idea who this rude little creature was?
Astute viewers will notice that while I was dealing with the fly situation, I was also providing transport to another, equally beautiful but much more polite hitchhiker: a Karner Blue that had come along and landed on my finger a few minutes earlier. I’m pleased to say I managed to both photograph and shoo the fly without disturbing my other passenger, who stuck around, lapping up my sweat, for a good quarter mile of trail.
How you want your letter signed:  Susan B.

Deer Fly

Dear Susan,
Thanks for your highly entertaining query.  You have been bitten by a Deer Fly.  According to BugGuide:  “Adults feed on plant nectar; females on vertebrate blood; larvae carnivorous and detritus feeders.”  You described their “incredible eyes”, and this BugGuide image beautifully captures the details of the eyes of a Deer Fly. Blues are one of the groups of butterflies that frequently have “puddle parties” on damp earth, a behavior beautifully described by Vladimir Nabakov in his fiction, and scientists believe they derive important minerals from this behavior.  We suspect your salty perspiration fulfilled your Karner Blue‘s need for moisture and minerals.

Karner Blue

What's That Bug? does not endorse extermination

Subject (please be succinct, descriptive and specific):  children’s book with male horsefly character
Date: 02/22/2020
Time: 04:08 PM EDT
Your letter to the bugman:  Hi – I’m writing a children’s book and one of the main characters is a male horsefly. I’ve been trying to find what types of plants male horseflies (specifically in the area of Kentucky) would be most attracted to.  I haven’t been able to find anything so far.  Any help would be appreciated.  Thank you.  Diana Wilburn

Male Black Horse Fly on Corn Leaf

Dear Diana,
Most of the images we have of male Horse Flies were not taken on plants, however, we did locate an image in our archives of a male Black Horse fly from nearby Indiana that was taken on the leaf of a corn plant.  According to BugGuide:  “adult females feed on vertebrate blood, usually of warm-blooded animals; males (also females in a few spp. in all 3 subfamilies) visit flowers.”  Of the Black Horse Fly,
Tabanus atratus, BugGuide notes:  “males, which lack mandibles, feed on nectar and plant juices.”  We suspect umble-shaped flowers in the family Apiaceae including parsley, carrots, dill and Queen Anne’s lace that attract many pollinating flies would also be a choice for Horse Flies, and we have images in our archive showing a Male Horse Fly (Hybomitra cincta) on a parsley blossom.  Other images we located online of male Horse Flies feeding on other umble blossoms include Nature Picture Library where it is on fennel, iStock Getty Images where the male Horse Fly is feeding on Hogweed, and Wikipedia where it states:  “they mainly feed on nectar of flowers (especially of Apiaceae species).”  Composite flowers in the family Asteraceae, are also good food sources including this Adobe Stock Images example of a male Horse Fly on Goldenrod or this Alamy image of a male Horse Fly on a coneflower.

Male Horse Fly on Parsley

Dear Daniel,
Wow what a detailed answer, thank you.  This is so helpful.
I also ordered a copy of your book.  Amazing what you learn and get interested in when you take a deep dive into something.
If/ when this books ends going to print I’ll definitely send a copy.
Thanks again
Good Luck with your book Diana.  We are glad we were helpful.


What's That Bug? does not endorse extermination

Subject:  Mysterious Tabanus
Geographic location of the bug:  Ottawa, Ontario, Canada
Date: 08/09/2019
Time: 10:08 PM EDT
Your letter to the bugman:  Hello bugman!
I found this large (1-1 1/2″) and very slow-flying horse fly on the trim of my car a few mornings ago. Only when I poked it with a stick did it finally fly around a bit and in a manner that almost reminded me of a bumblebee, flying with abdomen hangings down slightly. It stayed in the same area of our garage door for 24 hours. Every time my camera flash lit up, both for pre-flash and actual picture, the fly kind of jumped, as if it was scared or pained by the flash on my old Samsung A5 phone camera. But it never actually flew or even moved it’s feet much because of the flash, just sort of jumped on the spot.
I’m certain this is in the Tabanus genus thanks to a lot of googling, but cannot determine the species. The closest I can come is maybe Tabanus superjumentarius. Thoughts?
Thank you,
How you want your letter signed:  Mike L. in Ottawa

Horse Fly

Dear Mike L. in Ottawa,
We are going to go with
Tabanus catenatus which is pictured on BugGuide and is reported from Ontario on BugGuide.  The space between the eyes indicates this individual is a female.

Horse Fly

What's That Bug? does not endorse extermination

Subject:  green eyed wasp imposter
Geographic location of the bug:  Kiyikoy, Turkey
Date: 06/23/2019
Time: 04:41 AM EDT
Your letter to the bugman:  Can anyone tell me what this is and a bit more about it? I’ve been told it’s not a wasp and doesn’t sting but I don’t trust yellow and black flying things. It’s larger than a normal UK wasp.
How you want your letter signed:  Domino

Horse Fly

Dear Domino,
This is a Horse Fly in the family Tabanidae, and females bite larger animals like horses, cattle and other livestock, sucking blood as they feed.  They are opportunistic and will bite humans if there is no other available prey.  Based on Diptera Info, it might be
Tabanus promesogaeus and the person who submitted the images claims:  “Common and very ready to bite painfully as I know to my cost…”

What's That Bug? does not endorse extermination

Subject:  Grasshopper fly mix
Geographic location of the bug:  Enschede, The Netherlands
Date: 06/16/2019
Time: 08:00 AM EDT
Your letter to the bugman:  What’s the name of this bug? It appears to have two small “fangs” and rainbow colored eye’s, it’s not shy nor aggressive, i could easily touch it. Thanks.
How you want your letter signed:  Kevin Hoekstra

Female Notch Horned Cleg

Dear Kevin,
Though we were confident that this is a female Horse Fly in the family Tabanidae, there were enough features to cause us to consider it might be a member of a different family, but we quickly located the Notch Horned Cleg,
Haematopota pluvialis, on Influential Points  where it states:  “The female Haematopota pluvialis has distinctively patterned hairy eyes – the eye stripes extend over most of the eye.”  The site also states:  “There are of course innumerable accounts of Haematopota pluvialis biting man, especially in upland areas where clegs can turn a pleasant walk into an endurance course. Our own experience in the Scottish Highlands is that when the sun is out, the clegs bite; when the sun goes in the midges bite! Flight (and hence feeding) activity of Haematopota pluvialis is dependent on a sufficiently high humidity and temperature (Krčmar, 2004).”

Yes! That’s it, thank you! In Dutch it appears to be “Regendaas”.
Kevin Hoekstra

What's That Bug? does not endorse extermination

Subject:  Weird worm like creature found in water
Geographic location of the bug:  Petersburg, Tennessee
Date: 04/29/2019
Time: 09:20 PM EDT
Your letter to the bugman:  I was going outside catching tadpoles to grow and I can across this worm like thing. I scooped him up and put him in with the tadpoles. Maybe he wasn’t originally in the water and he fell in? But I didn’t want to take the chance. I’ve looked up tons of worm like creatures and even asked my parents to no avail. It would be appreciated greatly if you could help figure this mystery out. Thanks in advance.
How you want your letter signed:  Sierra

Horse Fly Larva

Dear Sierra,
We believe this is a Horse Fly larva.  According to Quora:  “
Most horse flies are associated with water, and the carnivorous larvae can be found therein. I have collected black horse fly larvae while searching through the muck and mud at pond edges. [T]Here’s a Colorado State University photo by Jennifer Bonnell of what is probably a black horse fly larva eating a small frog; they’ll also eat other insects, and, while I’ve never seen it, I’m sure they’ll eat any weakened or trapped minnows they might be able to.  Through the summer, the larvae grow in the water through 6–9 instars, and ultimately spend the winter in the the mud in their last instar. In spring, still in the muck and mire, they pupate and a few weeks later, the adults emerge.”  You might not want to keep this predatory Horse Fly larva with your tadpoles.

What's That Bug? does not endorse extermination