Horse Fly Lifespan: All You Need to Know in a Nutshell

Horse flies are notorious for their painful bites, causing discomfort to humans and animals alike. These robust insects can be found during warm months and are commonly seen around bodies of water. Understanding the lifespan of horse flies is crucial to preventing their bites and potential spread of diseases.

Adult horse flies can be quite large, ranging from 0.25 to 1.25 inches long, with distinctive compound eyes. Deer flies, on the other hand, are smaller counterparts but still pack a painful bite. They measure between 6-10 mm in length and are yellow to brown in color with patterned wings [1].

When discussing the horse fly lifespan, it is essential to look at their life cycle, which comprises four stages: egg, larva, pupa, and adult. Each stage contributes to the overall lifespan and will provide valuable information on how to manage these pests more effectively.

Horse Fly Lifespan and Life Cycle

Horse flies are known for their painful bites and can be quite a nuisance to both humans and animals. The life cycle of a horse fly consists of four stages: egg, larva, pupa, and adult.

• Egg: Female horse flies lay clusters of eggs on vegetation near water sources, often depositing hundreds of eggs at a time. These eggs are typically black or gray and can hatch within a week, depending on environmental conditions.

• Larva: After hatching, the larvae drop into the water or moist soil, where they start feeding on other insects, small invertebrates, and organic matter. This stage lasts several months to a year, during which the larvae grow and molt multiple times.

• Pupa: The fully developed larvae then form a pupal case and undergo metamorphosis. This stage can last from a few weeks to several months, also depending on temperature and humidity.

• Adult: Once the metamorphosis is complete, the adult horse flies emerge from the pupal case. They are strong fliers with a short lifespan, usually living only for a few weeks.

A primary comparison between horse flies and deer flies – their smaller counterparts – is presented in the table below:

To sum up the key points in this section:

• Horse fly life cycle consists of egg, larva, pupa, and adult stages.
• Eggs are laid on vegetation near water sources.
• The larval stage lasts several months to a year, while the pupal stage lasts a few weeks to several months.
• Adult horse flies have a short lifespan, living only for a few weeks.

Horse Fly Behavior and Appearance

Horse flies are known for their persistent biting behavior. Males and females exhibit different feeding habits. Males, for instance, feed primarily on nectar and plant juices. Females, on the other hand, have a blood-feeding behavior because they need additional nutrients for egg production.

Horse flies have distinct physical features. One key characteristic is their large compound eyes, which often display colorful purple or green bands. These vibrant colors make them easily recognizable.

Some of the most noteworthy features of horse flies are:

• Relatively large size (0.25 to 1.25 inches long)
• Robust body
• Prominent antennae
• A variety of color patterns, including all-black and various patterns on their abdomens and wings

Horse fly behavior varies among different species. For example, the smaller counterpart of the horse fly is the deer fly. Deer flies are 6-10 mm long, yellow to brown in color, and display patterned wings.

Here’s a comparison table highlighting the differences between horse flies and deer flies:

In summary, horse flies and deer flies exhibit distinct behavior and appearance characteristics. Their unique features, such as size, color, and biting behavior, help differentiate them from other flies. While there is variation among species, understanding their common traits allows for easier identification.

Horse Fly Bites and Effects on Humans and Livestock

Horse flies are notorious for their painful bites on humans and livestock. Their sharp mouthparts cut the skin, causing blood loss and discomfort.

The bites can lead to swelling, redness, and itchiness. In some cases, people may experience fever, dizziness, or weakness.

Livestock, such as horses and cattle, are common hosts for horse flies. They suffer from similar symptoms as humans when bitten.

Horse flies are known to be blood-sucking pests. Their bites have the potential to transmit diseases and infections.

Comparing the effects of horse fly bites on humans and livestock:

Some noteworthy points about horse fly bites:

• Painful for both humans and animals
• Can cause swelling and itchiness
• Potential to transmit diseases and infections
• Livestock are common hosts
• Bites may lead to fever and dizziness in humans

It’s essential to take preventative measures to protect humans and livestock from horse fly bites. For example, turning horses out at night instead of the day can reduce biting since the flies are active during the day.

Horse Fly Habitat and Breeding Grounds

Horse flies are commonly found in moist environments. They typically breed in standing water where the larvae can develop.

Examples of their preferred breeding grounds include:

• Ponds
• Swamps
• Wetlands
• Damp fields

These flies are affected by both temperature and weather. They thrive in warm climates, like Florida.

A comparison between North America and Florida habitats:

For effective control, remember to:

• Address standing water sources
• Monitor weather and temperature
• Understand regional differences

Keep these tips in mind, and good luck fighting horse flies!

Effective Horse Fly Control and Repellents

Horse flies can be quite a nuisance to both horses and their caretakers. There are various control methods which can help alleviate the problem. Here, we explore some effective approaches.

Sprays, Repellents, and Essential Oils

Sprays are a popular choice. You can use insecticide-laced fly sprays or natural repellents. Some examples of insecticides found in sprays are Coumaphos and Pyrethrins. These chemicals can efficiently repel and eliminate horse flies.

Natural solutions include essential oils. Eucalyptus, lavender, and tea tree oil are great options. Always make sure to dilute oils with carrier oils before application.

Traps and other Physical Measures

Traps attract and capture horse flies. There are several types, including sticky traps, light traps, and homemade traps. Examples of effective traps include H-Trap and the Horse Pal Fly Trap.

Physical exclusion methods can also help. Fly sheets, masks, and boots are great measures to prevent flies from accessing your horse. Fans in the stable area can disrupt flight too.

Some pest control strategies to consider:

• Regularly clean manure and eliminate standing water to prevent fly breeding.
• Use fans in the stable to disrupt fly flight.
• Rotate pastures to minimize horse fly populations.
• Use parasitic wasps as biological control agents.

Remember to practice integrated pest management (IPM) and combine multiple methods for optimal control.

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 – Horse Fly from Patagonia

horse fly from Patagonia, in Argentina and Chile
Sat, Jan 3, 2009 at 1:09 PM
Hi!
I´m sending a couple of pictures of a real nightmare in the forest of Patagonia during summer´s days. Its scientific name is Scaptia lata and the females are longer than one inch.
Local names are tabano negro or colihuacho
I must confess your site has been addictive to me since I discovered it and sent you my first message asking about a tiger? moth almost one year ago.
Happy New Year and many new bugs for you!
Mirta in San Antonio Oeste, Rio Negro. Argentina
Patagonian forests in Argentina and Chile

Hi Mirta,
Thanks for sending us these beautiful images of a gorgeous, but blood thirsty Horse Fly. Thank you also for including both the scientific name and local names. We don’t get many submissions from Argentina or Chile. Thanks also for your kind words regarding our humble site. That is a brave individual handling this female Horse Fly. Male Horse Flies do not bite, but the females will readily bite warm blooded creatures including humans.

Hi Daniel!
Thanks for your message
The brave one is me… but I need to tell you that the horse fly was a little dizzy after I punched it with my hand… So I took the picture while giving her time to recover and start flying again. Their bites are really painful, and it is impossible not try  knocking them when you are hiding quietly  to photography an elusive bird and you are pursued by almost 10 of them! Hope you don´t  think it was an unnecesary carnage… 🙂
I´d wish more websites like yours plenty of southamerican bugs. As you know, it is difficult to find places online  to ID our bugs. I will try to submit more when the pictures or the bug deserve it, if it is OK to you.
Hugs
Mirta

Update:  May 10, 2019
Daniel has been reading From So Simple a Beginning:  The Four Great Books of Charles Darwin edited by Deward O. Wilson and when he read in The Voyage of the Beagle on page 162 “A good-sized fly (Tabanus) was extremely numerous, and tormented us by its painful bite” he remembered this posting.l

Letter 2 – Timber Fly from Costa Rica

Subject: Giant True Fly
Location: Tortuguero, Costa Rica
May 21, 2013 2:31 pm
Hi Bugman,
I live in the coastal rainforest of Costa Rica and find all kinds of large and interesting bugs on a regular basis, but this was pretty impressive. I’m guessing she’s a female because there appears to be an ovipositor, but I don’t know much about Diptera. Hoping you can help!
Signature: Jennifer

Hi Jennifer,
WOW, that is some big Horse Fly in the family Tabanidae.  In addition to the ovipositor, you can tell she is a female because of the spacing between her eyes.  Male Horse Flies have no spacing between the eyes.  You Horse Fly looks somewhat similar to the mounted image of Myiotabanus muscoideus pictured on Sciency Thoughts, and that species is found from Mexico and Guatemala according to the site.  We have not been able to locate anything definite regarding the identification of your distinctly large Horse Fly, but perhaps one of our readers will have better luck.

Update:  January 21, 2014
Thanks to a comment from James, we now know that this is a Giant Wood Fly or Timber Fly in the family Pantophthalmidae, genus Pantophthalmus.  We located a matching photo on P-Base and on Panama Silvestre.

Letter 3 – Horse Fly from New Zealand

Subject: What type of fly is this?
Location: New Zealand
January 8, 2013 4:30 am
We saw this Large white fly in Northland NZ on 07/01/13 and wondered what it is. It was very placid and wasn’t afraid of us at all, in fact it jumped from the piece of wood we photographed it on, onto ond of us!! I have never seen one in New Zealand before. It was quite large and bigger than a typical NZ house or Blow fly.
Signature: Yours suncerely, Dion Brown

Hi Dion,
This is a Horse Fly or Gadfly in the family Tabanidae, a group that is commonly called March Flies in Australia.  The Insects of Tasmania website has several unidentified species that look very similar to your individual.  Female Horse Flies bite and feed on blood from large warm blooded animals, including people if there is no other food source, and males feed on nectar.

Letter 4 – Horse Fly: Chlorotabanus crepuscularis

Green bug!!!
Location: Central Florida
May 14, 2011 9:49 am
Have any idea what kind of bug this is? I live in Central Florida and they are only around this time of year. They are too smart…if they get into the house they fly into the walls repeatedly. Ugh! They buzz very loudly for a bug their size. Bzzzzzzzzzzzzzzzzz.
Hopefully someone can ID this bug and tell me how to send them away!!
Signature: Help!!!

Dear Help!!!,
According to BugGuide, this is Chlorotabanus crepuscularis, the only green Horse Fly in North America.  BugGuide also indicates:  “Females feed on mammalian blood” as well as providing this remark:  “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.”  Though we don’t normally provide extermination advice, we thought we would pass on the information about trapping them with dry ice, a fascinating method.  Also, the specimen in the photo is a blood sucking female who can be distinguished from the male by her eyes.  The eyes of a male Horse Fly meet at the center of the head while those of the female have a small space between them.

Thank you!!  They are a MILLION of them where I live (pretty rural).  I have never been bit by one though…luckily.  They seem to be attracted to light, too!!  I’ll try the dry ice though!!  Thanks!

Letter 5 – Horse Fly, Bee Fly or other????

Subject:  Flies
Geographic location of the bug:  Cootamundra, NSW. Australia
Date: 02/20/2018
Time: 12:55 AM EDT
Your letter to the bugman:  Wanting to know what sort of fly this is? Thank you.
How you want your letter signed:  Graham

Dear Graham,
Our initial thought is this must be a Horse Fly (called March Flies in Australia) from the family Tabanidae, but there are no similar looking images on the Brisbane Insects site.  The white edge on the compound eye is a trait found in several Bee Flies on the Brisbane Insect site that share that trait.  We are going to request assistance from our readership with this identification.

Letter 6 – Female Dark Giant Horse Fly from the UK

giant wasp, hornet?
Location: ebbw vale, south wales
July 7, 2011 2:50 pm
Hi, I noticed this massive bug that landed on my car I wondered what it was. It looked like a massive wasp at first glance, and some people I showed the photo to said it was a hornet, although I am not convinced. Please help identify the bug. Regards Gareth
Signature: gareth

Hi Gareth,
This is a Horse Fly and she is a female, which means she is a blood sucker.  Male and female Horse Flies can be distinguished by the eyes.   The eyes of the male are closer together while the eyes of the female are separated.  While we don’t know the exact species, we can tell you that Horse Flies are in the family Tabanidae.  The UK Safari website has a nice general page with information.

Update:  June 30, 2016
Today we posted an image of a male Horse Fly from the UK that we identified as a Dark Giant Horse Fly, Tabanus sudeticus, thanks to Influential Points.  This appears to be a female Dark Giant Horse Fly.

Letter 7 – Horse Fly from South Korea

Brightly Color Bee or Fly
Location: Camp Casey, South Korea
July 27, 2011 6:17 am
I have another one for you, this was taken on Camp Casey, South Korea. My husband and I came back to our vehicle to see this large fly/bee sitting on it. I’m wondering if it’s the South Korea horse fly you identified from another submission? This was was bright yellow in color though.
Signature: Sarah

More info on the pics I posted
July 27, 2011 6:22 am
I wanted to note, that all of the pictures I have submitted to you were taken this month, July 2011. Sorry I forgot to include that with my original submissions.
Thanks!
Signature: Sarah

Dear Sarah,
First, thank you for submitting each of your requests as separate submissions.  That makes our life so much easier when it comes to categorizing our archives.  This is indeed a Horse Fly, but we don’t know much about Korean species and we are unable to provide any additional information at this time.  We can tell you that it is a female based on the spacing between the eyes, and female Horse Flies are the biters.

Letter 8 – Horse Fly from Malaysia

Subject: Horse fly
Location: Penang Island, Malaysia
May 18, 2015 10:13 pm
I really enjoy browsing your site, so I thought I’d share these with you. I took these pictures yesterday evening. Based on what I could tell, this specimen appear to be a female horse fly though I’m not sure of the exact species.
Signature: Wei Nien

Good Morning Wei,
You are correct that this is a female Horse Fly.  A quick search online did not produce any visual matches in the family Tabanidae in Malaysia.

Letter 9 – Horse Fly from Mexico

Horse fly (with Lady Gaga shades)
Location:Tampico, Tamaulipas, México
September 15, 2010 1:18 pm
Hi there! What a great site you have here. This is my first post, i’m a bug fan myself and i’m constantly taking pictures of different bugs and looking for their scientific names. Sometimes I cannot find them, this is one of them.
I found it outside one of my classrooms at the university. The first thing that caught me were the fantastically multicolored eyes on this (a Tabanidae, I believe), but I wanted to know If there was a more specific name to it.
I took the pictures with my cellphone, so they’re as close as I could get to this fashionista fly.
Thanks!
Signature:  Rexnatus

Dear Rexnatus,
WE agree that this is a Horse Fly in the genus Tabanus, but we believe attempting to identify it to the species level may be beyond our capabilities.  Perhaps a Dipterist with a specialization in Tabanidae will write in.  Once the climate gets warmer in the southern portions of North America and close to the Central American divisions, there are certain species that are not as well documented on the internet and perhaps may not even be properly identified.  Not only are the eyes on this female Horse Fly (notice the space between her eyes) quite spectacular, but she has on black leggings.  We would love it if this was a new species that could be called Tabanus rexnatus.  Maybe she is not a distinct species, but rather a southern subspecies.  In that case she could be Tabanus unidentified gaga.

Karl has some thoughts
Horse Fly from Mexico
Hi Daniel and Rexnatus
Similar color patterns of the eyes and legs appear in a number of nearctic and particularly neotropical horse flies so I can’t be absolutely certain, but this really looks like a female Striped Horse Fly (Tabanidae: Tabanus lineola). I don’t know if the species is named for those amazing eyes or the prominent white dorsal stripe on the abdomen, a feature that is unfortunately not visible on the photo posted by Rexnatus. The species is found in the eastern and southern USA, as well as the Gulf Coast of Mexico. There are numerous images on the Bugguide, and a set of photos have been posted by Thomas Shahan on flickr. The latter photos are quite spectacular and show the striking differences between the female and male eyes. Regards.  Karl

Letter 10 – Horse Fly, but what species???

Robber Fly?
Location: Belleville, MI
August 31, 2011 11:09 pm
My Mom found this monster, recently-deceased fly today. Didn’t think it was a house fly…
Signature: Len

Hi Len,
We believe this is a Horse Fly, and its eyes indicate it is a female, but we are not certain of the species.  It does bear a strong resemblance to a mounted specimen on BugGuide that is identified as Whitneyomyia beatifica.  We are going to see if Eric Eaton can provide any information. 

Eric Eaton Responds
No, I’m pretty sure it is a species of Tabanus.  I’m not an expert on the group, though….
Eric

Letter 11 – Horse Fly

Subject: Yellow ”fly” with cicada-like wings
Location: Monteagle, TN
July 6, 2012 7:04 pm
I found this bug on a car in Monteagle, TN. The bug is yellow, and has wings like a cicada, but does not fly like one; it flies more like a fly. Is this a fly, or something else? Thanks!
Signature: Dan

Hi Dan,
This is a Horse Fly, and based on the close-set eyes, it is a male.  We believe we have identified it as Tabanus lineola, the Striped Horse Fly, based on this image from BugGuide.  Female Horse Flies can deliver a painful bite, but you have no reason to fear the males of the species.

Letter 12 – Horse Fly Exuvia, we believe

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

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.

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

Letter 13 – Horse Fly Eggs

Subject:  What’s this clutch?
Geographic location of the bug:  Southern Ontario
Date: 06/21/2018
Time: 08:19 PM EDT
Your letter to the bugman:  Looked up and saw this on a Norway Maple leaf.  Moist to the touch.   Looked like a fat little moth.  Actually made of overlaid cylindrical units.  Egg clutch?
How you want your letter signed:  Mike

Dear Mike,
These sure look like Horse Fly eggs to us.  Here is a BugGuide image for comparison.  According to Purdue University:  “Females search for a place to lay a single mass of eggs consisting of 100-800 eggs, depending on the species. Egg masses of most species that have been studied are laid on the underside of leaves or along the stems of emergent vegetation growing in wetlands. Hatching occurs in approximately 2-3 days, and newly emerged larvae drop down into water or saturated soil in which they feed and develop.” 

Letter 14 – Horse Fly from the UK

Subject:  Unidentifed Fly
Geographic location of the bug:  Somerset, UK
Date: 06/25/2018
Time: 06:45 AM EDT
Your letter to the bugman:  This fly was in my house in Somerset, UK this morning. I am unable to identify it because it was so large. The body was 35mm long. The eyes were green matt (olive/emerald). It buzzed loudly. This is much larger than the Giant Horse Fly known in the UK. Please can you help?
How you want your letter signed:  Liz

Dear Liz,
This is a female Horse Fly in the genus Tabanus.  Horse Flies often plague livestock by biting to feed on blood, but only the females bite.  We located an article on Huffington Post that states:  “Forget giant hogweed, horseflies are the newest atrocity plaguing the nation.  People across the UK have been sharing photos of their horrendous horsefly bites – and it’s enough to put you off your dinner.  The flies, which are large, dark-coloured and 1-1.2cm in size, are often found loitering around farm animals (such as horses and cattle), ponds and other grassy areas.  Their bites cut the skin, rather than piercing it, which can be very painful.”  Your fly might be the Dark Giant Horse Fly, Tabanus sudeticus.

Thank you for your quick reply. I am very familiar with our common horse flies but this one was nothing like them in size. This one was 3.5cm (35mm) long with a much wider body and not the normal 1-1.2 cm. I have also looked up the Dark Giant Horse Fly but the recorded maximum size for that type seems to be 2.5 cm. This was definitely something you would not like to bite you. I am now wishing I had trapped it rather than letting it go!
Many thanks for getting back to me.
Liz

Letter 15 – Horse Fly from Scotland

Subject:  Can you confirm my suspicion that this is a horsefly?
Geographic location of the bug:  Scotland
Date: 06/29/2018
Time: 02:17 PM EDT
Your letter to the bugman:  Hi, I have been finding these guys lying on their back in my back garden regularly (4 in the last 2 days). I thought they may have been honey bees.
I flipped them all back onto their feet only for them to roll back over.  It has been unusually warm here.
They are around 20mm in length.
I am a little concerned by the number of them appearing in my back garden because my 2 young children play there regularly.
Thanks in advance.
How you want your letter signed:  Kev

Dear Kev,
This sure looks like a Horse Fly to us.  The wing venation pattern matches the diagram posted to BugGuide.

Letter 16 – Horse Fly from Netherlands is Notch Horned Cleg

Subject:  Grasshopper fly mix
Geographic location of the bug:  Enschede, The Netherlands
Date: 06/16/2019
Time: 08:00 AM EDT
Your letter to the bugman:  What’s the name of this bug? It appears to have two small “fangs” and rainbow colored eye’s, it’s not shy nor aggressive, i could easily touch it. Thanks.
How you want your letter signed:  Kevin Hoekstra

Dear Kevin,
Though we were confident that this is a female Horse Fly in the family Tabanidae, there were enough features to cause us to consider it might be a member of a different family, but we quickly located the Notch Horned Cleg, Haematopota pluvialis, on Influential Points  where it states:  “The female Haematopota pluvialis has distinctively patterned hairy eyes – the eye stripes extend over most of the eye.”  The site also states:  “There are of course innumerable accounts of Haematopota pluvialis biting man, especially in upland areas where clegs can turn a pleasant walk into an endurance course. Our own experience in the Scottish Highlands is that when the sun is out, the clegs bite; when the sun goes in the midges bite! Flight (and hence feeding) activity of Haematopota pluvialis is dependent on a sufficiently high humidity and temperature (Krčmar, 2004).”

Yes! That’s it, thank you! In Dutch it appears to be “Regendaas”.
Regards,
Kevin Hoekstra

Letter 17 – Horse Fly from Canada

Subject:  Mysterious Tabanus
Geographic location of the bug:  Ottawa, Ontario, Canada
Date: 08/09/2019
Time: 10:08 PM EDT
Your letter to the bugman:  Hello bugman!
I found this large (1-1 1/2″) and very slow-flying horse fly on the trim of my car a few mornings ago. Only when I poked it with a stick did it finally fly around a bit and in a manner that almost reminded me of a bumblebee, flying with abdomen hangings down slightly. It stayed in the same area of our garage door for 24 hours. Every time my camera flash lit up, both for pre-flash and actual picture, the fly kind of jumped, as if it was scared or pained by the flash on my old Samsung A5 phone camera. But it never actually flew or even moved it’s feet much because of the flash, just sort of jumped on the spot.
I’m certain this is in the Tabanus genus thanks to a lot of googling, but cannot determine the species. The closest I can come is maybe Tabanus superjumentarius. Thoughts?
Thank you,
How you want your letter signed:  Mike L. in Ottawa

Dear Mike L. in Ottawa,
We are going to go with Tabanus catenatus which is pictured on BugGuide and is reported from Ontario on BugGuide.  The space between the eyes indicates this individual is a female.

Letter 18 – Horse Fly from the UK

Subject:  what is this
Geographic location of the bug:  Lancaster UK
Date: 07/01/2021
Time: 01:15 PM EDT
Your letter to the bugman:  hello
I live in Lancaster UK and found this big bug outside my window
what is it?
I know it’s not a great picture
it’s got massive eyes which it keeps cleaning and its about 1 or 2 inch long
I’m curious
How you want your letter signed :  thanks for your help, stef

Dear Stef,
This is a Horse Fly and it appears by the spacing of the eyes that this is a female.  Female Horse Flies are blood-suckers and they will deliver a painful bite.  We believe your individual may be a Dark Giant Horse Fly.