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

Subject: strange moth like bug?
Location: northern Virginia
July 18, 2016 12:12 pm
Hello! My mom and I noticed this bug on our outdoor umbrella and would like to know what it is. it’s a bit bigger than a grape, mostly black except for the eyes, which are sort of iridescent and translucent. it looks like a moth except for the eyes, which look like a fly’s. can you help?
Signature: signed, Julie

Male Black Horse Fly

Male Black Horse Fly

Dear Julie,
The close placement of the eyes indicates that this is a male Black Horse Fly,
Tabanus atratus.  There is a greater space between the eyes on the female Black Horse Fly.

What's That Bug? does not endorse extermination

Subject: Large wasp like fly
Location: West Cumbria , UK
June 30, 2016 6:25 am
A large flying insect landed on our balcony and I would like to know what it is. We live in Cumbria, UK and it’s the first time I’ve ever seen one of these before. I attach a couple of photos and it measures about an inch long. Can anyone identify this bug please?
Signature: P & K

Male Dark Giant Horse Fly

Male Dark Giant Horse Fly

Dear P & K,
This is a Horse Fly in the family Tabanidae and the large eyes with no space between them indicates this is a male Horse Fly.  It looks very much like this female Horse Fly from our archives, and we suspect they are the same species.  We believe we have correctly identified your species as the Dark Giant Horse Fly, Tabanus sudeticus, thanks to images on Influential Points where it states:  “The dark giant horsefly is distributed widely in northern Europe into Russia. In Britain it mainly lives in boggy areas in the north and west, although it is also quite common in the New Forest.”  A species page on Influential Points states:  “The dark giant horsefly flies in July and August and commonly feeds on the blood of cattle and ponies. In Europe …
Tabanus sudeticus flies from the end of June and through July and August. Krčmar (2005)  reports that it reaches its maximum abundance in third week of July. In Britain it mainly lives in boggy areas in the north and west, although it is also quite common in the New Forest. Tabanus sudeticus is distributed widely in northern Europe into Russia.”  Additionally, the site states:  “Tabanus sudeticus is anautogenous – it must first take a blood meal before it can lay eggs (Krčmar & Maríc, 2007 ). The dark giant horsefly undoubtedly prefers feeding on horses, cattle and deer, but it will bite man if available, as many have found to their cost. It makes a deep hum when flying around a host, but this stops abruptly just before it settles.”  If it is any consolation, only female Horse Flies are blood sucking biters.  Male Horse Flies take nectar.  BioPix has some excellent images of the Dark Giant Horse Fly.

Male Dark Giant Horse Fly

Male Dark Giant Horse Fly

What's That Bug? does not endorse extermination

Subject: What is this?
Location: New Haven MO
June 29, 2016 6:58 am
My kids found this in our yard. We live near New Haven, MO.
Signature: KyLee Diestelkamp

Horse Fly Exuvia, we believe

Horse Fly Exuvia, we believe

Hi again KyLee,
We already wrote back that this is the exuvia or cast off exoskeleton, but we were not sure of the species.  It sure looks Dipteran, or fly-like to us, so we continued to research.  We found this very similar looking exuvia on BugGuide that is identified as being from a Horse Fly.  We are pretty confident your kids found the exuvia of a Horse Fly.

Possibly Horse Fly Exuvia

Possibly Horse Fly Exuvia

Wow! Thank you so very much. I knew you folks could help us. Now we will look up the horsefly and study it.  I truly appreciate your time and effort.
KyLee

What's That Bug? does not endorse extermination

Subject: Unknown Fly
Location: Houston
May 11, 2016 9:22 am
Can you id this fly? About size of blow fly. Found outside warehouse, near septic tank.
Signature: Richard

American Horse Fly

American Horse Fly

Dear Richard,
We quickly identified your female Horse Fly on BugGuide as
Tabanus americanus, but we cannot fathom why it was not given the common name American Horse Fly based on its scientific species name.  According to BugGuide:  “Planet Earth’s largest tabanid.”  That would make it a pretty large Horse Fly.  Only female Horse Flies bite and feed on blood, and when there is no livestock available, they will bite humans.  The Encyclopedia of Life does refer to this as the American Horse Fly.

What's That Bug? does not endorse extermination

Subject: What is this bug?
Location: Valley
May 8, 2016 5:51 pm
Hello i live in california bakersfield and saw this bug and couldnt find out what it is can you identify it?
Signature: Caleb

Male Western Horse Fly

Male Western Horse Fly

Dear Caleb,
This is a male Western Horse Fly,
Tabanus punctifer, a species with pronounced sexual dimorphism, meaning the males and females can be mistaken for different species.  Here is a matching image from BugGuide.  The males have larger eyes with no spacing between them.  Only female Horse Flies feed on blood.

What's That Bug? does not endorse extermination

Subject: Biting fly
Location: Northern Uruguay
March 30, 2016 11:30 am
Hello. These are driving me crazy. and I finally got some pictures of them. The are pretty aggressive, circle around, then land on a leg and start biting. They produce painful swollen welts. They have been around from early summer through the fall. They appear to be territorial, yet they “hunt me” in pairs.
Any identification would be appreciated.
Thanks
Signature: Louis

Deer Fly

Deer Fly

Deer Fly

Deer Fly

Dear Louis,
Some of our more sensitive readers might want us to tag your submission as Unnecessary Carnage, but in our minds, blood suckers are fair game when it comes to battling with insects.  Interestingly only female Mosquitoes and Horse Flies flies suck blood, and the same holds for your Deer Flies in the Subfamily Chrysopsinae, relatives of Horse Flies in the family Tabanidae, like your individuals.  Males and females both feed on nectar, but females need blood before they are able to produce eggs.  Were you painting?  Was it oil or resin based paint?  We understand that some Beetles are attracted to fumes from paints and other solvents, but we don’t know if some Flies are similarly attracted.  You can get more information on Deer Flies on the Orkin site.

Four Deer Flies

Four Deer Flies

What's That Bug? does not endorse extermination