What Do Horse Flies Eat: Unraveling Their Diet Secrets

folder_openDiptera, Insecta
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Horse flies are known for their painful bites, but have you ever wondered what they eat? These bloodsucking insects can be a nuisance to humans, horses, and cattle alike. Understanding their diet can help us better prepare for encounters with these pesky pests.

Adult horse flies primarily feed on the blood of mammals, particularly large animals like horses and cattle. Their mouthparts are designed for cutting through skin, allowing them to consume blood as nourishment. Female horse flies, in particular, require blood meals for egg production. On the other hand, male horse flies, which do not bite, are more likely to feed on nectar and plant juices.

In contrast to the adults, horse fly larvae have a different diet. They are found in wet or moist environments and feed on organic matter, small insects, and other invertebrates. These aquatic or semi-aquatic larvae play an important role in breaking down organic materials in their ecosystem.

Understanding Horse Flies: An Overview

Horse flies are a part of the Tabanidae family, which consists of several species. These insects have unique characteristics, ranging from their size to painful bites.

  • Male horse flies often feed on nectar and pollen.
  • Female horse flies, on the other hand, require a blood meal to reproduce effectively.

Horse flies vary in size, usually ranging between 3/4 to 1-1/4 inches long. Their color can be different, some having clear wings, and others with solidly colored wings.

  • Their eyes are often brightly colored.
  • Their antennae are typically short and stout.

The wings of horse flies may have dark patterns, adding to their distinct appearance. In addition to their four legs, horse flies are known for their painful bites. These bloodsucking insects can be serious pests for humans as well as cattle and horses. Here are some quick facts about horse flies:

  • Horse flies are daytime biters.
  • They may appear near wooded edges or marshy areas.
  • Their bites can be painful due to a scissor-like mouthpart.

It’s important to understand these key identifiers to help protect yourself and animals from unpleasant encounters with horse flies.

Habitat of Horse Flies

Horse flies are commonly found in environments close to water sources such as marshes and streams. These areas provide the perfect breeding ground for their larvae, which require a moist environment to thrive. When selecting a habitat, horse flies are attracted to:

  • Marshes
  • Streams
  • Forests near water sources
  • Wet meadows

You might find them in areas with slow-moving water, where their larvae can feed on other aquatic insects and organic matter. Human activity can also influence the abundance of horse flies in certain locations, as some species are able to complete development in low-oxygen environments resulting from water pollution or organic waste build-up.

Keep in mind that horse flies are not limited to these habitats. They can travel long distances in search of blood meals from animals or humans, causing them to be a nuisance in various environments. To better understand how horse flies and their habitats differ, take a look at the following comparison table:

Habitat Horse Flies Deer Flies
Marshes Common Common
Streams Common Common
Forests Less common Common
Meadows Less common Common

So, when you’re spending time outdoors, make sure to be prepared for encounters with horse flies, especially around marshes and streams, and take necessary precautions to protect yourself and your animals from their painful bites.

Diet of Horse Flies

Horse flies are known for their painful bites and can be a nuisance to humans, livestock, and other animals. Their diet varies between males and females, as well as other factors.

Male Horse Flies

Males primarily feed on nectar from flowers. They’re not known for biting, so they don’t pose much threat to humans or animals. Examples of their nectar sources include:

  • Wildflowers
  • Grasses
  • Fruit blossoms

Female Horse Flies

Female horse flies, on the other hand, feed on blood as their primary source of nutrition. They need blood meals for reproduction. Their prey includes:

  • Livestock (cattle, horses)
  • Mammals (deer, dogs)
  • Birds
  • Humans

Female horse flies are known for their painful bites. They use their sharp mouthparts to slice the skin and lap up the blood. Their bites can cause significant discomfort and sometimes lead to infections.

Female horse flies feed on both stationary and moving hosts, targeting vulnerable areas such as the legs, head, and shoulders.

To sum up:

Horse Fly Gender Diet
Male Nectar
Female Blood & Nectar

So when encountering horse flies, it’s essential to remember that while the males are mostly harmless, the females can pose a threat due to their painful bites and potential to spread diseases. Use protective measures such as fly sheets and masks for your animals or insect repellent on exposed skin to minimize the risk of bites.

The Role of Gender in Horse Flies’ Diet

Horse flies are known for their painful bite, but did you know that their diet varies depending on gender? In this section, we’ll explore the different feeding habits of male and female horse flies.

Male Horse Flies

Males are far less aggressive than their female counterparts, and they don’t bite humans or animals for a blood meal. Instead, they prefer a diet that consists of:

  • Pollen
  • Nectar

Typically, male horse flies feed on nectar from various flowers, which provides them with the energy they need for their daily activities.

Female Horse Flies

On the other hand, female horse flies have a more complex dietary requirement. While they also consume pollen and nectar like males, they have an additional need for blood meals. This requirement comes from the fact that female horse flies need the protein found in blood to reproduce and develop their eggs.

Due to their biting and bloodsucking behavior, female horse flies can be a nuisance to humans, livestock, and horses. They often target large mammals but can also bite humans if given the opportunity.

In summary, the diet of horse flies is influenced by their gender. Male horse flies primarily feed on pollen and nectar, while female horse flies also require blood meals for reproductive purposes. This distinction in feeding habits is essential to understand, especially when dealing with these pests and developing control methods.

The Life Cycle of Horse Flies

Horse flies are bloodsucking insects that feed on mammals, including humans and livestock. Their life cycle consists of four distinct stages: eggs, larva, pupa, and adult. Let’s explore each stage in more detail.

In the egg stage, female horse flies lay their eggs on vegetation near water sources. This is because the hatching larvae require a moist environment to thrive.

Once the eggs hatch, the larval stage begins. Larvae are aquatic or semi-aquatic, living in wet areas like ponds, marshes, or wet soil. They are predatory, feeding on other small insects and even other horse fly larvae.

As the larvae grow and develop, they eventually reach the pupa stage. During this phase, they become more sedentary and form a hardened case around themselves. Inside the pupal case, their bodies undergo a metamorphosis, transforming into adult horse flies.

When the transformation is complete, the adult horse flies emerge. At this stage, they are focused on two primary activities: feeding and reproduction.

  • Feeding: Female horse flies require blood meals for egg production, while males feed on nectar and plant sap.
  • Reproduction: Mating occurs during the adult stage, with females usually laying their eggs shortly after feeding.

Horse flies have a relatively short lifespan, with adults living only a few weeks. Despite their brief existence, they are capable of causing discomfort and stress to livestock and humans due to their painful bites and relentless pursuit for a blood meal. It is essential to take preventive measures to protect yourself and your animals from these pesky insects.

Interactions of Horse Flies with Other Species

Horse flies are known for their persistent and painful bites, making them a nuisance for various species, including mammals, humans, pets, and livestock. They seek out hosts to feed, and their prey and predators have unique relationships with these pests.

Mammals and Livestock
Horse flies primarily feed on the blood of mammals. They are attracted to large, dark-colored animals such as horses, cows, and deer. As a result, they pose a significant problem for farmers and livestock owners. Some impacts of horse fly bites are:

  • Reduced milk production in dairy cattle
  • Decreased weight gain in cattle and horses
  • Transmission of diseases such as anaplasmosis in cattle

Humans and Pets
Horse flies can also bite and irritate humans and pets, like dogs and cats. They can disrupt outdoor activities due to their painful bites, which might cause allergic reactions in some individuals.

Prey and Predators
Horse flies, despite their aggressive nature towards hosts, also serve as prey for certain species. For example, birds, frogs, spiders, and some species of wasps feed on horse flies. These predators help control the horse fly population, reducing their impact on affected species.

Comparison Table

Features Horse Flies vs. Other Flies
Size Larger
Bite Painful
Hosts Mammals, Humans, Pets
Prey Birds, Frogs, Spiders

In summary, horse flies create a challenging situation for hosts, causing discomfort to humans, pets, and livestock. However, their role as prey for certain predators helps maintain a natural balance in the ecosystem.

Symptoms and Treatment of Horse Fly Bites

Horse fly bites can cause various symptoms in both humans and animals. If you experience a horse fly bite, the initial pain might be sharp due to their piercing and slashing mouthparts. Swelling, redness, and itching may also develop around the bite area.

In some cases, individuals may experience more severe reactions like dizziness, fever, wheezing, or a rash. It’s essential to monitor your symptoms and seek medical attention if they worsen or become concerning.

To treat a horse fly bite, you can take the following steps:

  • Clean the area with soap and water to prevent infection.
  • Apply a cold compress or ice pack to reduce swelling and alleviate pain.
  • Consider using over-the-counter pain relievers or anti-inflammatory medications if needed.
  • Apply topical treatments like hydrocortisone cream or calamine lotion to help with itching and discomfort.

It’s crucial to avoid scratching the bite area, as this may lead to infection. Additionally, protect yourself from horse fly bites by using insect repellents, wearing protective clothing, and avoiding areas where horse flies are common.

Remember, the key is to monitor your symptoms closely and seek medical attention if necessary. Stay prepared and protect yourself from painful horse fly bites.

Horse Flies as Disease Vectors

Horse flies are known to bite animals and humans, leading to potential infections and diseases. These pests can transmit various pathogens, but thankfully, some of the most dangerous diseases don’t have direct links to horse flies.

You might have heard of West Nile virus and Lyme disease. While these pathogens have been isolated from female horse flies, there’s no evidence that they transmit them to humans source. However, one species of deer fly in western U.S. has been linked to transmitting a different bacterium that causes illness source.

When horse flies bite, they create an open wound, which might lead to secondary infections. It’s essential to take care of the bite area and keep it clean. Furthermore, their bites can often cause allergic reactions, which can range from mild irritation to severe symptoms.

Remember to follow these points when dealing with horse fly bites:

  • Clean the wound immediately
  • Use an antiseptic or antibiotic ointment
  • Apply a cold compress (if required)
  • Keep an eye on the area for any signs of infection or allergic reaction

By understanding the role of horse flies as disease vectors, staying alert, and taking proper precautions, you’ll reduce the risk of contracting infections from their bites. Stay safe!

Preventing and Handling Horse Fly Infestations

To prevent horse fly infestations, you can:

  • Use repellents designed for horses and humans, like a permethrin-based spray for horses and DEET for humans.
  • Set up traps around your property, such as sticky traps or the H-Trap.
  • Clean animal enclosures regularly, since horse flies are attracted to manure and organic waste.

To lessen the impact of flies on your horse, consider these options:

  • Turn your horses out at night instead of daytime, as horse flies are usually active during the day.
  • Provide shelter or canopy trees away from wooded edges or marshy areas, where horse flies tend to breed.

Effective horse fly traps vary and can include:

  • Commercial fly traps like the H-Trap, which are designed specifically for horse flies.
  • Homemade fly traps, using a combination of vinegar, soap, and water to attract and trap flies.

Limitations when using traps and repellents:

  • Traps won’t eliminate every single fly, but they can reduce the overall fly population.
  • Insect repellents, even when applied properly, aren’t always foolproof. Some direct contact with flies may still occur.

In conclusion, a combination of traps and repellents, along with vigilant cleaning and strategic pasture management, can help you reduce the impact of horse fly infestations on your property.

Global Distribution of Horse Flies

Horse flies can be found in various regions across the world. In the U.S, around 160 species of horse flies have been identified, with Indiana alone having at least 45 species1. Worldwide, there are approximately 4,300 species of horse and deer flies combined2. They are common in different geographical regions and are known to thrive in areas that are humid, warm, and close to water sources.

Different species have found their niches in various ecosystems. For example, you can find horse flies in:

  • Temperate regions
  • Near wetlands and swamps
  • Along forest edges
  • Around agricultural fields

In some regions, certain species of horse flies can become a significant concern for livestock owners and people, as the females need a blood meal to reproduce effectively3. The bites can impact animal welfare and health and can also transmit diseases in some cases. To protect yourself and your animals, it’s essential to be aware of the local presence of these pests and implement appropriate control measures.

Unique Characteristics of Horse Flies

Horse flies are more than just a nuisance. They have some distinctive features that make them stand out among other flies. Here are some unique characteristics of horse flies that might fascinate you or make you wary of them.

  • Fast and aggressive: Horse flies are known for their speed and aggression. They are relentless and persistent in pursuing a target, whether it’s a horse or a human.

  • Large size: These flies can grow up to 1-1/4 inches long, making them one of the larger types of flies you might encounter.

  • Distinctive appearance: Horse flies have clear or solidly colored wings and brightly colored eyes, setting them apart from other fly species.

  • Biting and bloodsucking: Female horse flies need a blood meal to reproduce, making them dangerous and annoying pests to humans and animals alike. Their bite can be quite painful due to the scissor-like mouthparts they use to cut through the skin.

  • Cannibalistic tendencies: Although not commonly known, horse flies can exhibit cannibalistic behavior, particularly when other food sources are scarce.

Here’s a comparison table highlighting some of these unique characteristics:

Characteristic Description
Size Up to 1-1/4 inches long
Appearance Clear or solidly colored wings, brightly colored eyes
Behavior Fast, aggressive, persistent, annoying
Feeding habits Bloodsucking, sometimes cannibalistic

Keep these characteristics in mind when dealing with horse flies. Your awareness of their unique traits can help you better understand their behavior and take appropriate precautions when outdoors.


  1. Horse and Deer Flies | Public Health and Medical Entomology | Purdue University

  2. Horse Flies and Deer Flies | Entomology – University of Kentucky

  3. Horse Flies – Home and Garden IPM from Cooperative Extension | University of Maine

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Male Horse Fly


Subject: Interesting fly
Location: North Kingstown, RI
July 21, 2014 6:47 am
This fly (at least I think it’s a fly) was on my car in North Kingstown, RI on July 20, 2014. I’ve never seen one like this before.
I tried searching google images, but nothing came up that looked like this.
Can you tell me what it is?
Signature: Gary Brownell

Male Horse Fly
Male Horse Fly

Hi Gary,
The close-set eyes indicate that this Horse Fly in the family Tabanidae is a non-biting male.  Biting female Horse Flies have a space between the eyes.  See this Horse Fly eye comparison from our archives.  A dorsal view would make species identification easier.

Thanks. I guess I’ve never looked closely at one of these before. It was the white eyes that caught my attention…
Gary Brownell

We believe the faceted eyes are most likely not pigmented white, but rather reflecting the light from the sky.

Interesting. They didn’t seem to change color as the fly changed position. Unfortunately, I only got pictures from this one angle, so I can’t be sure about all that in hindsight. But it was definitely the white eyes that drew my attention.
Gary Brownell

Letter 2 – Red Footed Cannibalfly eats American Horse Fly


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

Letter 3 – Striped Horse Fly


Fly I Have Never Seen Before
Tue, Oct 14, 2008 at 5:20 AM
Bugman, I resent the pictures I originally sent yesterday. Hopefully they are larger. Hi Bugman, I was sitting on my front porch this summer (June maybe) and this little one flew onto the banister and did not move even when I went to touch it. I have never seen a fly like this before or since. I live in Illinois. Love your site.
Fly Curious
Homer Glen, Illinois

Striped Horse Fly
Striped Horse Fly

Dear Fly Curious,
First, thanks for sending the larger photographs.  The original tiny files were not very good for exact identification.  This is a male (we believe) Striped Horse Fly, Tabanus lineola.  According to BugGuide you can distinguish between the sexes this way: “Females: pale median stripe on abdomen bordered by dark submedian stripes; eyes with 3 green bands; scutellum concolorous with thorax
Males: body pattern similar to females; eyes bare (no hairs) with large upper facets sharply differentiated from smaller lower facets; costal cell of wing clear; prescutal lobe paler than rest of thorax; palps white ”

Striped Horse Fly
Striped Horse Fly

Letter 4 – Male Green Horse Fly


Subject: Green Horse Fly
Location: Palm Coast, Fl
May 14, 2013 11:23 am
I saw this guy flitting about the plants near my house and he had me rather baffled to what he is. Thanks to your site I was able to identify him as the Green Horse Fly and also found out he was the harmless male (phew!). He made for a great bug model though, let me get real close without a worry. Bugguide says that only females seek out mammalian blood, so I guess males go after nectar of some sort? He was very interested in the wild flowers, and that’s where I lost sight of him. I love this site and I hope you guys like my photos.
Signature: Monica Velazquez

Green Horse Fly
Green Horse Fly

Hi Monica,
We really do love your photo of a male Green Horse Fly,
Chlorotabanus crepuscularis, the only green member of the family in North America.  You can tell by the closely spaced eyes that your Green Horse Fly is a male.

Green Horse Fly
Green Horse Fly

Letter 5 – Male Horse Fly: Chlorotabanus crepuscularis


Subject: What kind of insect is this?
Location: Wesley Chapel, Florida
April 11, 2015 7:42 am
Hello Bugman,
I have a butterfly garden in Florida and have found many strange insects but cannot figure out what this little guy is.
Any information is much appreciated!
Signature: Michele M.

Male Horse Fly:  Chlorotabanus crepuscularis
Male Horse Fly: Chlorotabanus crepuscularis

Dear Michele,
This is really a gorgeous image of a male Horse Fly. We verified its identity as
Chlorotabanus crepuscularis on BugGuide where it states: “Females feed on mammalian blood.  …  As with all the blood-feeding tabanids, the females are responsive to Carbon Dioxide. I caught over 500 females in one night with a trap baited with dry ice in coastal South Carolina. Will also come to lights at night.  Regarded as a pest species in Florida.”  The closeness of the eyes indicates that this is a non-biting male Horse Fly.  Female Horse Flies have a space between the eyes.

Wow!  A horse fly!
I never would have guessed!
I love insects and never use pesticides.  I just love seeing their beauty up close.
Thanks so much for your speedy answer and expertise,
Michele Mistretta

Letter 6 – Mystery Thing is Horse Fly Egg Mass


Subject: What am I?
Location: Pennsylvania
June 5, 2015 10:13 pm
Can’t seem to find what this guy is.
Signature: Heather Cookson

Mystery Thing
Horse Fly Egg Mass

Dear Heather,
Your mystery thing has us quite stumped.  It does not look like an insect, but it appears that it might have been produced by an insect.  We do not believe this is an egg mass, but it might be some type of shelter.  The “scales” look somewhat like seeds.  Could you please provide more details on where it was found and regarding its size.  Perhaps one of our readers will be able to contribute some valuable information.

Update:  Horse Fly Egg Mass
Immediately after posting, we received a comment identifying this as a Tabanid or Horse Fly Egg Mass, and a link to BugGuide.  Mystery solved thanks to a diligent reader. 

Eric Eaton Confirms
Hi, Daniel:
That is a batch of horse fly or deer fly eggs.
author, Kaufman Field Guide to Insects of North America

Letter 7 – Male Western Horse Fly


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.

Letter 8 – Probably Horse Fly Larva


Subject: Mysterious “swimming bug”
Location: Salina Turda in Romania
July 31, 2016 2:31 am
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.

Letter 9 – NOT Beyonce’s Horse Fly, but Probably Horse Fly from Malaysia


Challenge to our Readers:  Help us identify this striking looking Fly

Subject: Giant Malaysian Fly
Location: Malaysia
October 2, 2016 8:03 am
I’ve seen this fly on occasion and am unable to identify it. It’s the largest fly I’ve ever seen, around the size of a large deer fly, around 1.5 inches in size. Though I think I’ve even seen as big as 2 inches.
They have shiny, bluish backs, and about 1/4 of the end of their abdomen is yellow. They are generally slow.
Signature: Alex

Horse Fly, we believe
Horse Fly, we believe

Dear Alex,
We have not had any luck finding similar looking images online, but we believe this is a female Horse Fly in the family Tabanidae.  Interestingly, our searches did bring up images of a “gold butt” Horse Fly that was captured in 1981 in Australia and has recently been named after pop diva Beyonce.  According to Asian Scientist:  “A previously un-named species of horse fly with golden hair on its lower abdomen has been named in honor of pop diva, Beyoncé – a member of the former group Destiny’s Child.  AsianScientist (Jan. 13, 2012) – A previously un-named species of horse fly with golden hair on its lower abdomen has been named in honor of pop diva, Beyoncé – a member of the former group Destiny’s Child, that recorded the 2001 hit single, Bootylicious. According to the Australian National Insect Collection researcher responsible for officially ‘describing’ the fly as Scaptia (Plinthina) beyonceae, CSIRO’s Bryan Lessard, the fly’s spectacular gold color makes it the ‘all time diva of flies.'”  The site also notes:  “‘It was the unique dense golden hairs on the fly’s abdomen that led me to name this fly in honor of the performer Beyoncé as well as giving me the chance to demonstrate the fun side of taxonomy – the naming of species,’ Mr Lessard said.”  Weekly World News also picked up the story and notes:  “CANBERRA, Australia — A newly discovered horse fly in Australia was so ‘bootylicious’ with its golden-haired butt, that entomologists named it: Beyonce.  Previously published results from Bryan Lessard, a 24-year-old researcher at Australia’s Commonwealth Scientific and Industrial Research Organization, were recently announced on the species that had been sitting in a fly collection since it was captured in 1981 – the same year pop diva Beyonce was born.”  Though your fly shares the striking gold butt, your individuals blue body and black wings make it an even more striking looking fly.  We hope our readers will take up this challenge and write to us with their findings.

Hi Daniel!
I appreciate the quick reply!  I did a Google search with the “gold butt” Horse fly name, and saw what you’re referring to.  It’s similar in appearance, but not identical.  I don’t know if that means they’re related?  The main difference is that the fly I found is completely hairless.   If you guys want, I can capture one (next time I see one… I see them once every few months) and send it to you.   I sometimes find them dead, and can prepare a specimen for you (if you let me know how. 🙂 ).

Hi again Alex,
Let’s let our readership attempt to identify your fly before we resort to capturing a specimen.

Letter 10 – Male Hippo Fly from South Africa


Subject: ID Please
Location: East London, South Africa
February 12, 2017 11:52 am
I received a mobile photo of a rather large fly-like insect that I’m trying to identify for interest sake.
I have attached 2 cropped shots (sorry for poor quality) of the insect. It’s eating on a piece of apple, and a regular house fly can be seen in the background.
The photo was taken in East London, South Africa. Climate is coastal hot and humid.
I’d really appreciate it if you could try ID it for me please.
Many thanks
Signature: Kevin Durst

Male Horse Fly

Dear Kevin,
Because of the large eyes, this Horse Fly in the family Tabanidae can be sexed as male.  We found a similar image on iSpot, but it is only identified to the family level.  Female Horse Flies are blood suckers that commonly trouble livestock, and will bite humans if no four legged hosts are available.  Males only feed on sweets, mainly from fruits and nectar from flowers.

Hi Daniel,
Thank you for such a quick response, and for your identification and information…I really do appreciate it.
I asked on a Facebook page dedicated to insect I.D. too, and it’s confirmed as Tabanus biguttatus, known locally as a Hippo Fly.
Best Regards

Thanks for the species name assistance Kevin.  We actually have a well-researched Hippo Fly posting in our archives.

Letter 11 – Male Horse Fly: Tabanus sudeticus


Subject: Tabanus sudeticus
Location: Parkhill Inclosure. The New Forest. Hampshire
June 27, 2017 9:55 am
Hi. I have some pictures of a male Tabanus sudeticus, from The New Forest. What I’d like to know is – has the fly secreted this liquid? It didn’t seem to be feeding on it as I approached & didn’t move at all when I was taking photos. Thank you in advance.
Signature: Teresa

Male Horse Fly: Tabanus sudeticus

Dear Teresa,
Thanks for sending in your images of a male
Tabanus sudeticus.  According to Influential Points:  “Males of Tabanus sudeticus (not shown here) have the abdomen extensively yellow-orange. The facets in the upper two thirds of the compound eye of Tabanus sudeticus are, with the exception of those on hind margin, at least four times the size of the rest. ”  We know that many insects secrete fluids when they emerge from the pupal stage.  Your male Horse Fly is in prime physical condition.  Perhaps he just emerged and secreted fluids, and you took his images before his first flight.

Male Horse Fly: Tabanus sudeticus


Letter 12 – Male Timber Fly from Costa Rica


Subject:  What is this?
Geographic location of the bug:  Caribbean side of Costa Rica
Date: 02/15/2018
Time: 09:18 AM EDT
Your letter to the bugman:  This bug is about an inch and a half long. The body is orange-ish.  It came out at night but was still here in the morning.
How you want your letter signed:  Sherry Lidstone

Male Timber Fly

Dear Sherry,
This is one beautiful fly, and the large eyes indicate it is a male Fly.  Our best guess is that it might be a male Horse Fly, but we have never seen any images of Horse Flies with such unusual markings.  Perhaps one of our readers will be able to assist us with a proper identification.

Thanks to Cesar Crash, we now know that this is a male Timber Fly in the family Pantophthalmidae.  We have images of a female Timber Fly in our archives.

Letter 13 – Possible Horse Fly Larva from salt pans in France


Subject:  Salt loving bug
Geographic location of the bug:  France https://goo.gl/maps/pVi4sfjzn6F2
Date: 03/09/2018
Time: 01:08 PM EDT
Your letter to the bugman:  Hi,
Whilst on holiday in France a couple of years ago we visited the salt pans I’ve located above. Whilst there we found what we think is a beetle larvae that the salt seller told us lived in the salt. Any ideas what it is? the lady told us that they are “prehistoric”.
How you want your letter signed:  Cheers, Martin & Ruth

Fly Larva we believe

Dear Martin and Ruth,
We do not believe this is a Beetle larva.  It looks to us more like the larva of a Fly in the order Diptera, possibly a Horse Fly.  We will attempt further research on this.

Fly Larva we believe
Thanks Daniel, it does look like some of the hose fly larvae pictures, i just can’t find any references to salt loving species. This one literally lived in pure salt!!

Letter 14 – Striped Horse Fly


Subject:  Deer fly?
Geographic location of the bug:  Whitmore Lake, MI
Date: 07/14/2018
Time: 10:12 AM EDT
Your letter to the bugman:  Hello your Bugness,
Is this a deer fly?  It’s not orange like descriptions I’ve read.
How you want your letter signed:  Curious in Whitmore Lake

Striped Horse Fly

Dear Curious in Whitmore Lake,
Deer Flies and Horse Flies are in the same family, Tabanidae, and your individual is a Horse Fly.  The space between the eyes indicates it is a blood sucking female.  Only female Horse Flies and Deer Flies Bite.  Males do not bite.  We believe we have identified your female Horse Fly as a Striped Horse Fly,
Tabanus lineola, thanks to images posted to BugGuide.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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Tags: Horse Fly

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