Black horse flies are a type of large, robust biting fly commonly found near bodies of water. These creatures are known for causing irritation and discomfort to both humans and animals alike. With their considerable size and pesky nature, it’s essential to understand how to identify and manage their presence effectively.
One key characteristic of black horse flies is their enormous compound eyes, often displaying colorful purple or green bands against a blue or yellowish-green background source. Additionally, they can vary in size, ranging from 0.25 to 1.25 inches long, and even come in different color variations depending on the species source.
Black horse flies breed in non-polluted water with high levels of dissolved oxygen, so their larvae and pupae can be found in various aquatic habitats such as large rivers, mountain streams, creeks, and waterfalls source. Understanding these key traits can help with the identification and control of black horse flies on your property, ensuring a reduction in their painful bites and annoyance.
Identification and Habitat
Color and Appearance
The Black Horse Fly (Tabanus atratus) is a large fly, typically measuring about 1 inch in length. Its key features include:
- Body color: Black or dark brown
- Eyes: Large and green or purple
- Wings: Translucent with a dark tint
Range and Habitat
Black Horse Flies are commonly found in North America, particularly in the eastern and southern United States. Their preferred habitats include:
- Ponds
- Marshes
- Damp woods
Distinguishing Black Horse Fly from Deer Flies and House Flies
Here’s a comparison table to help distinguish Black Horse Flies from Deer Flies, and House Flies:
| Feature | Black Horse Fly | Deer Fly | House Fly |
|---|---|---|---|
| Size | ~1 inch | ~1/4-1/2 inch | ~1/8-1/4 inch |
| Color | Black or dark brown | Brownish-yellow with dark bands | Gray with dark stripes |
| Eyes | Large, green or purple | Large, brightly colored | Small, red or brownish |
| Wings | Translucent, dark tint | Translucent, dark bands | Translucent, no tint |
By noting differences in size, color, eyes, and wings, it becomes easier to identify a Black Horse Fly in comparison to Deer Flies and House Flies.
Life Cycle and Reproduction
Eggs and Larval Stages
Black horse flies begin their life cycle as eggs. Females typically lay clusters of 25-1,000 eggs on surfaces that are close to water, such as aquatic plants or wet soil.
- Eggs are dark-colored and difficult to spot
- Hatching occurs within 5-7 days
Upon hatching, the larvae emerge and immediately begin feeding on organic matter. They play an essential role in breaking down waste and other organic materials in the ecosystem.
- Larvae are known as maggots
- They undergo several molts to become larger
Livestock can be impacted by the larval stage, as black horse fly maggots can infest wounds or sores on animals, leading to potential infections.
Pupation and Adult Stage
Arthropoda, like black horse flies, undergo pupation and become adults. Larvae pupate in moist soil.
- Pupation lasts 1-2 weeks
- Adult black horse flies emerge from soil
Once they become adults, they focus on reproducing. Female horse flies require a blood meal to produce eggs, which may come from humans or wildlife.
- Females are attracted to large mammals for their blood meal
- Males feed on nectar and don’t bite animals or humans
| Life Stage | Time Frame | Characteristics |
|---|---|---|
| Eggs | 5-7 days | Dark, near water |
| Larvae (maggots) | Several months | Feed on organic matter |
| Pupation | 1-2 weeks | Moist soil |
| Adult | Varies | Females require blood meal; Males feed on nectar |
In conclusion, understanding the life cycle and reproduction of black horse flies is essential for their management and controlling their impact on livestock and humans.
Feeding and Impact on Humans and Animals
Biting Mechanism and Pain
Horse flies are known for their painful bites. They use their scissor-like mouthparts to cut through the skin and consume blood. The sensation of being bitten by a horse fly can be compared to a sharp pinch or a stab.
- Painful bites due to scissor-like mouthparts
- Comparable to a sharp pinch or stab
Female Horseflies and Blood Meals
Female horse flies primarily target mammals as their source of blood meals. They can detect their prey through the emission of carbon dioxide. Some common targets include humans, horses, and livestock. Male horse flies do not bite and instead feed on nectar.
- Female horse flies need blood meals for reproduction
- Mammals, including humans and livestock, are targeted
- Male horse flies do not bite
Impact on Livestock and Horses
Horse flies can negatively impact livestock by causing discomfort, stress, and even disease transmission. One such disease is Equine Infectious Anemia (EIA), also known as swamp fever. This disease can cause severe anemia in horses and may have no cure.
Comparison Table: Mosquito vs. Horse Fly Bites
| Mosquito Bite | Horse Fly Bite |
|---|---|
| Not very painful | Painful |
| Can carry diseases | Can carry EIA |
| Slow fliers | Fast fliers |
In conclusion, horse fly bites are not only painful but can also lead to severe health consequences for humans and animals alike. Keeping animals in well-screened enclosures and using repellents can help minimize the risk of horse fly bites.
Bug Control Recommendation Tool
Prevention and Control
Insect Repellent and Fly Traps
Using insect repellent is a practical method to deter black horse flies from biting. They can be applied directly to the skin or clothing. For instance, DEET-based repellents are typically effective against tabanidae species.
Fly traps can also be a useful solution for controlling black horse flies in outdoor areas. Examples include the sticky fly trap and the homemade water traps.
Protective Clothing and Environmental Measures
Wearing light-colored clothing can help minimize the risk of black horse fly bites. Covering up exposed skin areas with loose and long-sleeved clothing is advisable when spending time outdoors in fly-prone areas.
Environmental measures can also be taken to reduce breeding sites, such as eliminating standing water and maintaining clean surroundings. Proper waste management and removal of decaying organic materials also contribute to limiting horse fly populations.
Managing Fly Populations on Livestock and Farms
For livestock owners, various strategies can be adopted to lessen the impact of black horse flies. Some measures include:
- Applying fly repellents designed for animals, such as sprays or ointments
- Installing fly traps around the farm to reduce the number of adult flies
- Properly managing manure and waste to prevent breeding sites
Fly control on farms also involves maintaining clean surroundings, such as removing spilled feed, soiled bedding, and decaying grass clippings or hay.
Comparison Table: Insect Repellent vs. Fly Traps
| Method | Pros | Cons |
|---|---|---|
| Insect Repellent | Offers personal protection against horse fly bites | May require reapplication, may not be effective against all fly species |
| Fly Traps | Capture and reduce the number of adult flies in an area | May not be sufficient in high-fly density areas, may require frequent cleaning and maintenance |
Overall, a combination of insect repellent, fly traps, protective clothing, and environmental measures can effectively manage black horse fly populations and help you avoid painful bites. Remember always to monitor your surroundings and take precautions when outdoors during horse fly season.
Horse Fly Bites and Health Risks
Symptoms and Reactions
The black horse fly (Tabanus atratus) is a large, harmful insect belonging to the family Tabanidae and order Diptera. Found in humid areas like Florida, it is typically active during daylight hours in hot summer months. A black horse fly bite can cause various symptoms in humans and animals.
Some common reactions include:
- Sharp pain, as their mandible and hooks tear the skin
- Swelling
- Redness
- Itching
These reactions are due to the chemicals released by the fly to access the blood meal. In some cases, more severe symptoms may occur, such as:
- Difficulty breathing
- Dizziness
- Allergic reactions
Infections and Diseases
Black horse flies can also transmit infections and diseases, particularly in horses. The most concerning infection is Equine Infectious Anemia (EIA), also known as swamp fever.
Symptoms in horses may include:
- Fever
- Weakness
- Weight loss
Black horse flies can transmit EIA when they feed on an infected horse and subsequently on an uninfected one. The risk of infection is higher in areas with large horse fly populations, such as Canada and the wetlands of Florida.
Treatment and Remedies
After a black horse fly bite, it is essential to clean the wound to prevent bacterial infections. Over-the-counter treatments can help alleviate itching and swelling. Generally, affected individuals can use:
- Ice packs or cold compresses for swelling
- Antihistamines for itching and allergic reactions
- Analgesics for pain relief
In conclusion, the black horse fly is a harmful insect that can cause painful bites, swelling, itching, and sometimes severe reactions. It can also transmit Equine Infectious Anemia in horses. Avoiding horse fly habitats, using insect repellents, and treating bites appropriately can help minimize the risk and impact of these unwanted pests.
Interesting Facts and Resources
The black horse fly belongs to the Tabanidae family, which consists of over 4,000 species, including deer flies and horse flies. These flies are known for their painful bites and transmit diseases among livestock animals.
Identification:
- Large and robust size (0.25 to 1.25 inches long)
- Huge compound eyes
- Colorful bands on eyes
- Abdomen and wing patterns vary by species
Here is a resource to help identify and learn more about horse and deer flies.
Facts:
- Males prefer nectar, while females rely on blood meals for egg production
- Active during daylight hours
- Attracted to carbon dioxide and movement, making animals and humans targets
Horse and deer flies are found in a diverse range of aquatic habitats. These habitats include large rivers, mountain streams, creeks, and waterfalls.
Range:
- Widespread across North America
- Active from May to September in Wisconsin with over 30 species found in the region
Resources:
- Penn State Extension: Filth Fly Control on Horse Farms
- Texas A&M University: Horse Fly, Deer Fly
- Purdue University: Horse and Deer Flies
| Feature | Horse Fly | Deer Fly |
|---|---|---|
| Size | 0.5 to 1.25 inches long | 0.25 to 0.5 inches long |
| Flight | Straight and fast | Erratic and slow |
You can control flies by reducing breeding sites and using insecticides when necessary. Moreover, repellents can protect both humans and livestock from these pests.
 |
 |
| Male Black Horse Fly | Female Black Horse vFly |
66 Comments. Leave new
I found one in Chatham Ontario. Canada is that normal?? I’ve never seen one before?
You live withing the range of the Black Horse Fly. Interestingly, we just posted a new photo of a Black Horse Fly a few minutes ago.
I found one of those huge black flies on my third floor balcony this morning here in Peterborough, Ontario. Why is it that most of us have never seen these giants?
I saw one today in Greely, Ontario. It was so large I thought it was a moth.. Lol
glad the males don’t bite at least 🙂
I saw one today in Greely, Ontario. It was so large I thought it was a moth.. Lol
glad the males don’t bite at least 🙂
Thank you so much, bug experts! I found one of the guys during my shift at the local park. We have plenty of water, but no livestock like the poster.
I found your black horse fly here of u can contact me back …
I just killed one of those today in South Dakota. It landed on my horses and was biting her. I smashed it with my cell phone. Dirty buggers.
Spotted one large, definitely female, on my front porch here in Bossier, Louisiana. Ours is the only watered lawn so with the temps I wasn’t shocked to see a horsefly, or one of thst size, as we’ve had an unusually large amount this year. The difference was the striking solid black and it seemed bigger than the usual 1-1/2″ , so maybe it was 2″, but I threw everything out of my hands to get inside because I know even small regular horseflies HURT and I swear it appeared like came from hell itself. Gladly I can sleep knowing now that they’re somewhat recognized and not biblical.
In new orleans just had one in my car. They are massive
This looks EXACTLY like the ones that hang out around my front porch this time of year…lots of bright sun and my porch rails are painted deep dark black. These flies are enormous and zoom in like stelth bombers but do well to avoid me and sit still for extended periods. Saw one today at least 1-1/2″x1/2″ and at close observation appeared to be covered in fur. Though I live in the country where there may be horses or cattle, I only have seen flies like this on my porch.
One of these giants landed on the back of my horse today. It looked like a black hummingbird at first, because there was no way that was a regular horse fly. When I looked more closely, it looked like a fly on steroids, except jet black with translucent black wings.
We have them here on Long Island .I call them black back bugs(For lack of a better description) . LOL They land on the horses back and I have seen the stingers come out and dig into their spines or butt causing the horses to buck and run to try to get away. The bugs will follow them. They are horrible.
We have been seeing them only lately here in the northern New Jersey area, mostly in our woods. And yes they do follow/ chase us ! One landed on our dog and she kept trying to eat it. Ugh. Monstrous.
I lived on Long Island all my life, never saw them. I moved to SC 5 years ago, and the bugs are huge ! Saw this black fly 3 times in the last 2 days. No horses around, and they chase you.
Live in NE Iowa just N of Decorah.
My dog was outside working at killing a small mouse,(I thought), but it was this huge black fly! It resembled a horse fly. I had a plastic bag in my hand and when I saw it was not a mouse but a fly I had never seen before, I picked it up with the bag and put it in a jar. It was missing a leg and one wing was askew, but very alive.
I am 63, lived in this area all my life and have never seen this bug!
Live in NE Iowa just N of Decorah.
My dog was outside working at killing a small mouse,(I thought), but it was this huge black fly! It resembled a horse fly. I had a plastic bag in my hand and when I saw it was not a mouse but a fly I had never seen before, I picked it up with the bag and put it in a jar. It was missing a leg and one wing was askew, but very alive.
I am 63, lived in this area all my life and have never seen this bug!
We had one of these HUGE flies by the front door tonight! All black approx. 1.5 inches long. Big mouth, ugh!
Oops, forgot to give my location. Central Oklahoma.
Northern NY, 1000 islands area. Found on back deck. Same size and color as described in other posts. We have fly shooters, (sorry bug lovers) and my husband is a pro with them!! This is one fly that won’t be bothering the baby calves next door any longer!!
We also just had a very large black fly on our truck liner. We had to look it up and found out what he is on your website. We are in New Hampshire.
I have a picture
I just took a picture and a video of one of these flies. I didn’t know what it was. I had to look up big black flying bugs. It is beautiful.
One flew into my SUV in central Illinois, freaked me out.
We just saw one of these in the yard by the pool. My son won’t go back out to clean up now. We are in the northern Ca. Are they afraid of anything or what can I kill it with from afar?
We do not provide extermination advice.
We live in London Ontario Canada. Just saw a massive black fly. Looked like a house fly but the size of a small cockroach. The one pictured above was definitely the same kind. A 40 year old country kid, this is the first time I’ve ever seen one. Thank you for the information.
Just saw one on deck flower box in Paducah, KY. I appreciate the ID tips and photos.
I have an all black horse and moved him to a new boarding facility this past Fall. This spring, I have been seeing these ENORMOUS flies. While other flies, horseflies, etc. bounce off my freshly fly sprayed boy, these atrocities just land on his back and torment him. They’re QUICK too! It’s easy to swat horseflies with my hand but these are too quick!
I use a homade fly spray with Skin So Soft, apple cider vinegar, water and essential oils. I may try regular commercial sprays to see if they work. Anyone else have something that works?
I have an all black horse and moved him to a new boarding facility this past Fall. This spring, I have been seeing these ENORMOUS flies. While other flies, horseflies, etc. bounce off my freshly fly sprayed boy, these atrocities just land on his back and torment him. They’re QUICK too! It’s easy to swat horseflies with my hand but these are too quick!
I use a homade fly spray with Skin So Soft, apple cider vinegar, water and essential oils. I may try regular commercial sprays to see if they work. Anyone else have something that works?
Just had one on the back passenger window when I went to put my baby in his carseat. I freaked out bc I had no idea what it was. We ended up jumping n through the driver side nd that sucker stayed there till we got to the corner.
I live in the middle of Maryland and saw one of these today on my car. I had never seen one so large, but we have had the worst year in along time for horse flies. It’s the first year I’ve considered getting a fly blanket for my horse. Now I feel like I want to wrap all our horses from head to toe in some protection with that monster flying around. Guess I need to go get a case of liquid Benadryl for the barn along with a gallon of lidocaine for the pain. On horses and cows the welt can be anywhere from 2 to 4 inches in diameter and stays sore for weeks.
We just found one of these on our pool deck in Eastern Massachusetts. How bad is the bite from one of them?
Horse Fly bites are reported to be quite painful. Though it concerns British Horse Flies, this Huffington Post article has some information on the bite of a Horse Fly.
just found one in aurora il i got it in a powerade bottle if i had known it was dangerous i wouldve left it alone lol
I just saw one of these today in Southern New Hampshire.
I just saw one of these today in Southern New Hampshire!
Hi, I’m from Baltimore, Maryland. I saw a huge all black horse fly in my backyard today! I live in the city and I have an urban garden. My vegetables are all growning in containers. There are no farm animals in my area. I was able to get a picture.
I just chased one out of my house. Opened the door to let my car in and he was trying to catch it. Thought it was a big moth at first until I got a good look at it. Biggest damn fly I have ever seen. I love North of Boise Idaho.
According to BugGuide, the Black Horse Fly is an eastern species. We suspect you encountered a Western Horse Fly, Tabanus punctifer.
Just saw one of these large black flies for the first time on my property of 40 years. It was lethargic and clinging to a twig as I moved it around. I am in South East Texas. I thought it was just bigger because it was Texas 🙂 . Your comments have been helpful.
We have one in our house right now. My husband tried to get rid of it last night and he wound up putting a hole in our wall and gave up.
We live in a rural area of Florida and all our neighbors have livestock. We don’t even have a dog, but our 3 kids are wild enough to be considered animals.
We had an incident last night where the fire rescue had to come and they left our door open, which is where we think this beast of a fly came in. It is solid black and I thought it was a large moth at first. Then when my husband saw it, he said that it was a black horse fly. So of course I looked it up and scared myself to bits. I immediately took off my dark blue dress because it is attracted to large dark objects.
Well, woke up this morning to get the kids ready for school, and wouldnt you know, that darn fly is sitting on the wall next to the light. Today is the day!
We have one in our house right now. My husband tried to get rid of it last night and he wound up putting a hole in our wall and gave up.
We live in a rural area of Florida and all our neighbors have livestock. We don’t even have a dog, but our 3 kids are wild enough to be considered animals.
We had an incident last night where the fire rescue had to come and they left our door open, which is where we think this beast of a fly came in. It is solid black and I thought it was a large moth at first. Then when my husband saw it, he said that it was a black horse fly. So of course I looked it up and scared myself to bits. I immediately took off my dark blue dress because it is attracted to large dark objects.
Well, woke up this morning to get the kids ready for school, and wouldnt you know, that darn fly is sitting on the wall next to the light. Today is the day!
https://www.facebook.com/tim.schafer.9421/videos/10157189052669693/?t=1
my black bug!! Swansea SC!
https://www.facebook.com/tim.schafer.9421/videos/10157189052669693/?t=1
my black bug!! Swansea SC!
Just saw one of these in Big Prairie Ohio. I did not like the looks of it. A lot of farms around here. Thanks for the info.
Found two giant ones in my pool! I live in Waterford Michigan !!
Glengarry ON, just saw one last week with my husband on our back porch. We have never seen anything close to the size of this. Very scary! To think these could sting too? Unimaginable!
Horse Flies do not sting. They bite.
JUST SAW ONE–NO HORSES WITHIN TWO MILES.I HAVE NEVER SEEN THE LIKES OF IT BEFORE. YORKTOWN HEIGHTS NEW YORK
Everyone is posting that they either have seen or that they have the bugs around their home. However no one has said what the bug is or if it can bite/sting you. If someone knows please let everyone know what it is or may be please. Thank You,
Brian W.
Everyone is posting that they either have seen or that they have the bugs around their home. However no one has said what the bug is or if it can bite/sting you. If someone knows please let everyone know what it is or may be please. Thank You,
Brian W.
are these flies harmful to plants or animals?
Female Horse Flies bite and suck blood from larger mammals, but plants are perfectly safe around them.
Growing up poor, in the South in the 50’s, we spent much of our summertime outside entertaining ourselves doing the usual kid stuff. We would catch the big Black Horsefly, tie a length of thread around its neck, holding on to one end, we’d let them go and fly them around. It was fun!
Hi I live in Cape Town South Africa out in a town called Wellington and we found this fly on our horses today. Never new the live here and they carry virus and bacteria
One of these flew into my house late last night
here in St Augustine, FL.
Just found one here in Davie, FL. Female. There are horse stables nearby.
I have them in my backyard in Delaware. Why have I never seen this book before? I’m 54 years old. LOL.
Yes we have them now too, they have never been around here before. Green heads and sheep fies are bad enough but now these too whats going on..
Just had one get inside my mothers house. And I’m in Florida.
Hi there, I hope someone reads this in 2021! 🙂 I was hoping someone might know about any diseases this fly might be able to transfer to hu.ans….?… I’m personally dealing with a situation concerning possible parasitic infection; and I’ve been seeing this “fly” hanging out for the last 3 days. It’s not dead, I know for sure cause when I took It’s picture, it stirred it up a bit….Anyway, thought I’d give my hopes and luck a shot here at your site and forum. 🙂 Thank You Truly,
L Crystal R
Ps from L Crystal R…I cannot seem to figure out how to post a picture of the creature ! I’m still trying ~
You may submit images using the Ask What’s That Bug? link on our site.
Got bitten in Jacksonville, Florida. The bug is the same color as matte black bumper on vehicle as I just saw again Today after I got chomped twice three days ago.
The wounds swelled, still itch & with blood scars formed.
Richmond,VA Just saw one for the first time in my 70 years. It must have been at least 1 1/2 inches. Sat on the window frame for about 10 minutes then moved on.