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

Subject: Big cool fly
Location: Exeter, NH
August 19, 2016 5:45 am
Hi,
I saw this on my car this morning. I wanted to know what it was. Thank you.
Signature: Cheryl

Male Black Horse Fly

Male Black Horse Fly

Hi Cheryl,
This is a male Black Horse Fly,
Tabanus atratus.  According to BugGuide:  “Very wide range of habitats; generally near aquatic environments (Long 2001). Requires moist environments in which to lay eggs, and mammals to feed on (Long 2001). Larvae live ‘along the margins of ponds and ditches.'”  BugGuide also notes:  “Females feed on mammalian blood; males, which lack mandibles, feed on nectar and plant juices (Long 2001). Especially prone to attack cattle and other livestock.”  When livestock are not available, female Horse Flies will bite humans.  You can tell your individual is a male because of the large, close-set eyes.  Female Horse Flies have a space between their eyes.

What's That Bug? does not endorse extermination

Subject: Impressive killer
Location: California, ky. 20 minutes south of cincinnati
August 14, 2016 6:42 pm
Hello, I found a photo of the insect in question on the Internet and it directed me to your page. I couldn’t find the image I saw on your web site, so I am contacting you. This insect was flying around with a horse fly in its grips and eventually landed on me…. Then on one of my banana trees, where he rested for at least a half hour (see pic). You are welcome to use my images on your web site as they are quite interesting.
Signature: Thanks, Tony Painter

Red Footed Cannibalfly eats Horse Fly

Red Footed Cannibalfly eats Horse Fly

Dear Tony,
This impressive predator is a Giant Robber Fly known as a Red Footed Cannibalfly,
Promachus rufipes, and they are adept hunters who can take very large prey on the wing.  There is even a report on the Hilton Pond Center website of a Red Footed Cannibalfly catching a hummingbird.  We believe the prey in your awesome images is Tabanus americanus, because of the red antennae.  Can you confirm that the Horse Fly has green eyes?  They are not readily visibly green in your images.  We are very impressed that you were able to walk around this awesome Food Chain encounter to get images from both sides.  As an aside, we had never heard of California, Kentucky, and we learned that as of the 2014 census, your sity has a population of 87.

Red Footed Cannibalfly eats Horse Fly

Red Footed Cannibalfly eats Horse Fly

What's That Bug? does not endorse extermination

Subject: Mysterious “swimming bug”
Location: Salina Turda in Romania
July 31, 2016 2:31 am
Hello,
Could you help us with the identification of this one?
During the holidays in Romania (salt mines called Salina Turda) we found a strange worm in one of the outdoors swimming pools. It was floating on the surface and at first we thought it’s a piece of plant, but then we noticed it was “shaking”. There was about 8-10% salinity in the water, so we took the bug outside, worried that it may be in pain. Later we put it into the wet mud, near the salty pools and normal river, so it could return to salt waters if it in fact was its natural enviroment.

Some facts about the worm:
– It wasn’t longer than five cm. No legs, no visible eyes nor mouth, only small bump and long stick from the other side.
– Its “skin” was really soft in touch, but on the sides of the body it had sharp ridges and small spikes.
– It was moving in a really strange way, using this long stick (tail?) to push itself. He was suprisingly fast outside of the water. When bothered, it was freezing with it’s tail holded upright.
– More about the tail, it has few tiny hair on the end.

Some more facts:
– It was the middle of July (18th).
– Except of those salt pools, there was plenty of normal water.
– People around didn’t recognize the species.

Can you help us? We wish we could knew what it was.
Signature: Tourists

Probably Horse Fly Larva

Probably Horse Fly Larva

Dear Tourists,
This is definitely Dipteran, and we believe it might be a Horse Fly Larva.

What's That Bug? does not endorse extermination

Subject: Hover fly in Scotland
Location: Scottish West Highlands
August 2, 2016 10:58 am
This creature was about 1 inch long, seemed really massive! I’m in the West Highlands of Scotland. It also seemed on its last legs but disappeared after a while.
Signature: Alison

Female Dark Giant Horse Fly

Female Dark Giant Horse Fly

Dear Alison,
This is a female Dark Giant Horse Fly,
Tabanus sudeticus, and you can tell she is a female by the spacing between her eyes.  Your three different views are a wonderful way to provide an excellent identification guide for our readership.  According to Influential Points, it is also known as the Dark Behemothic Horsefly.

Female Dark Giant Horse Fly

Female Dark Giant Horse Fly

Thank you so much. Lots of people guessing at my photo on Facebook but none of us got it right. I’m posted your link. Thank you!

Female Dark Giant Horse Fly

Female Dark Giant Horse Fly

What's That Bug? does not endorse extermination

Subject: I know it’s not a fly.
Location: Lebanon, IN. cornfield
July 26, 2016 8:34 pm
I’ve asked anyone and everyone. “It’s just a horse fly” , I know thats not it. This thing is so bizarre. It would fill a gatoraid cap perfect. Its all black with orange on the feet. Humungus grey orbs for eyes. I’d really love to know what it’s called. If I’m wrong, so sorry and thank you.
Signature: Laura Kniola

Male Black Horse Fly

Male Black Horse Fly

Dear Laura,
“Just a horse fly” is so dismissive of a magnificent family of flies, but this is in fact a male Black Horse Fly.  Male Horse Flies have enormous eyes with no space between them, which is an easy way to distinguish between the sexes.  Only female Horse Flies are blood-sucking biters, and they have a distinct space between their eyes.

What's That Bug? does not endorse extermination

Subject: What type of fly is this?
Location: Chatham, ON, Canada
July 26, 2016 6:31 am
Hi. Recently, I took a picture of this fly on my car and I’m not sure what kind it is. Most people say it’s a horse fly but I’m not sure. Any idea?
Signature: Al

Horse Fly

Horse Fly

Dear Al,
This certainly is a Horse Fly, and upon scrolling through BugGuide pages, we believe we have correctly identified it as
Tabanus stygius.  According to BugGuide‘s data, this wide ranging species is found in Ontario.  We cannot tell from your image if this is a female or a male as the space between the eyes is not visible, but only female Horse Flies are blood-sucking biters.

What's That Bug? does not endorse extermination