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What the heck kind of horrific flies are these?

This year we are having an exceptionally bad year of small biting flies. We’re in MO, if this helps anyone. They look like stable flies, but they come in clusters and they pack a nasty bite. None of the horses want to go outside, and they swarm in my outdoor. I’m trying to figure out how to get rid of them, but none of the normal fly sprays etc. even touch them. Are they small horseflies? We have the bombers too, but these are little. Black flies? I thought those were mostly a spring thing.

Any ideas?

No idea, here is the Missouri state article on horse and deer flies with pics in it.

Thanks - yeah, I’ve seen that but these are stable fly sized, just real nasty biters. I didn’t think stable flies bit like that, but maybe it’s just the kind that are here. They leave small lumps that eventually form a scab.

I just bought traps to see if I can make a dent. But if they are black flies apparently I’m hosed since they travel like 10 miles to torture animals. They were not this bad last year, but this year they are out something fierce. I’m not sure if the drought then heavy rains caused it and they just hatched all at once or what.

They could be deer flies? I’m in VA and this is the season for them. They bite, and it HURTS. They are also VERY sticky and hard to dislodge. I basically don’t hack out this time of year because of them.

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Maybe? The ones we used to have in PA (where I’m originally from) were more green & brown. These are black/gray like a stable fly, and smaller than the deer flies we had there. They aren’t tiny like a midge. They aren’t huge like a horse fly either, I know those suckers.

We are in a wooded area, border a state park and there are a lot of deer around, plus we’re less than a mile from the Mississippi River. So - the aquatic types of flies are in abundance, which leads me to believe it’s “more” than a stable fly.

They are really really bad in my grass arena. To a lesser extent in the paddocks. Not bad in the barn but I have fly control and fans going there.

Any chance you could get a picture of one?

I’m in MIssouri too but I’m not seeing what you’re describing. So far lots of stable flies, face flies, bot flies, horse flies, and deer flies.

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Around here, GA, they are attracted to the thinner skin horses and will draw blood. Fly spray will just work for a few hours. They look just like a house fly except these have some serious teeth. I’ve been bit through a sock before. What I call them I wouldn’t type here.


That’s exactly what I’m describing. They bite through shirts - freaking miserable buggers.

They look just like stable flies, only they bite like a mofo. I’ll try to get a picture of them. They are worse when it’s hot. I just went and did some ground driving and they were biting, but not mobbing like they were yesterday. I mean - behind the horse you can see multiples of them just biting the heck out of the horse. If you wear shorts, your legs will be covered in bites.

Maybe they are just stable flies and I didn’t have such bitey ones in PA. We’ve had a lot of storms lately so potentially a lot of vegetation for them to breed in. Manure management is well away from where they swarm and we’re working on getting it off property entirely (I finally procured a dumpster).

Fly spray does exactly zero things to these guys. I’ve sprayed them directly and I swear they just rubbed their legs together and thanked me for the shower. The only thing I’ve figured out so far is keeping the horse well covered in sheets, but it’s friggen hot, so that’s not great either.

Southern Middle Tennessee here.

I have myriads of house flies and have seen a few very black small flies that bite thru my heavy socks.

All that helps my horses is the 42” drum fans blowing on them in the barn. Fans are pushing hot air but they don’t care.

They put themselves on night grazing and choose to stay in the barn all day — eating hay.

If you can’t use big fans, I hope you figure something out.

We’ve got fans, stall and aisle blowing and that is where they are comfortable. I just feel badly that they are stuck in the stall. I don’t have the option for them to choose, so it’s either me shove them out and they beg to come in, or leave them in and feel guilty that they are inside all day.

Nighttime turnout doesn’t seem to be an option either because of pop-up storms and the mosquitoes that are so bad that they cause huge lumps on the thin-skinned chestnut. Maybe we can try again with sheets tonight. Gah.

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We can all hope for an early frost and winter doesn’t g


We have something similar here in NJ…we’ve never had such a bad fly season. I’ve literally bought 7 different types of sprays this past month and nothing is helping!! My horses in fly sheet and boots are running like maniacs on the bad days. Some days I have to wait until it’s dark, as they will still be running at 8 pm!

We have the usual biting/black flies, deer flies, greenheads, and mosquitos. I’ve not yet seen the giant black horse flies (I call them the B52 bombers…they land on the middle of their backs). And these new ones are like a mini biting fly and seem to be immune to spray (I’ve tried Flysect with deet, deep woods off, Fly Bye, Pyhrana, Ecovet, and some rub ons).

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We are having a similar time in Pa this year. Worst year for flies I can ever remember.
My pastured are always a little buggy, gnats mainly but this year the black flies are in the barns and the horses are NOT having them. I’ve never seen the horses so antsy standing in crossties. I almost never fly spray (mainly for farrier, trail riding and before I go in the show pen) but I’ve been fly spraying all the horses even just to brush them.
My fly paper is full within 12 hours of putting them up. Im ready for winter!


Could they be horn flies? We had good luck this year with Fly Bye spray.

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We have these near Ottawa, Canada. Not sure what they are, but they do really hurt!! They don’t cluster too badly around here, but they seem to come in cycles. They like to cluster around the belly, midline and groin of my horses and I find a swipe of SWAT every day is effective.

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Severe Season for Biting Flies

You do have to turn off your content blockers, but it is a free article.

This article is in reference to Colorado, but it explains why biting insects have been so bad this year in certain areas. Apparently a large number of larva don’t typically make it to the adult stage due to drying out. This year, however, several areas of snow-melt and excessive rains didn’t allow the larva to dry out, resulting in a noticeable increase in these insect populations.

The article also mentioned stable flies and described them similarly to your swarming, biting flies.

As if the smoke from Canada this year wasn’t bad enough, now we have people in different states saying that it’s one of the worst years for biting insects. Yuck.

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I’ll try that! Heck, I’ll try anything! They sound like horn flies, but when I read the description black flies, horn flies & stable flies all seem like possibilities.

Either way, they are vicious!

I just bought a bunch of traps as well. We didn’t need any last year. This year, it’s bad!

I’m in Ontario, Canada and we’ve always had those. They look just like a regular stable fly, but bite! I think they’re usually out this time of year and not all summer. From what I remember, they don’t stay around for long.


I agree. That’s been my experience in the Ottawa area.

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Like Glitterless I have those too. Not very many this year for some reason. Maybe extremely dry weather? Maybe birds pecking and spreading out manure in the pasture thus exposing the eggs to the sun and heat? I don’t know why. I find they bite mostly on the legs and they HURT. I don’t think they have a limited existence - I think that they are usually around all summer and fall. Not horn flies. I sometimes get those when we have big storms and they blow in from the cows about a half mile down the road.

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