How to Keep Horse Flies Away from Your Pool: Simple and Effective Tips

Horse flies can be a nuisance, especially when you’re trying to enjoy a relaxing day by the pool. These pesky insects are not only annoying, but they also pose a risk of transmitting diseases. It’s important to find effective ways to keep them at bay and maintain a comfortable swimming environment.

Various methods can be employed to deter horse flies from your pool area. Some of these include managing water sources, providing shade, and utilizing traps or insecticides. By implementing a combination of these techniques, you can reduce the presence of these irritating pests and make the most of your outdoor space.

Understanding Horse Flies

Habits and Characteristics

  • Horse flies are daytime biters.
  • They typically breed in moist, sunny areas near the water.
  • Female horse flies require a blood meal to reproduce.
  • They are known for their painful bites.

Male and Female Differences

  • Male horse flies:

    • Do not bite
    • Feed on nectar and pollen
    • Have large, wrap-around eyes
  • Female horse flies:

    • Bite and feed on blood
    • Require a blood meal for egg production
    • Have separated eyes

The Tabanidae Family

  • Horse flies belong to the Tabanidae family.
  • Tabanidae also includes deer flies.
  • Both horse flies and deer flies are vectors for diseases.

Comparison Table: Horse Flies vs. Deer Flies

Feature Horse Flies Deer Flies
Size Moderate to large (14 to 19 mm long) Small to medium (10 to 13 mm long)
Wings Clear Tinted smokey gray-brown or patterned
Thorax Grayish-brown Greenish-yellow with dark stripes
Disease Transmission Possible Possible

Preventing Horse Flies Around Your Pool

Eliminating Standing Water

Standing water attracts horse flies, so reducing or eliminating it is crucial. Check the area around your pool for standing water regularly, and clear any buildup. Common sources of standing water include:

  • Pool covers
  • Buckets or containers
  • Low-lying areas in the grass

Remember to keep your pool cover tightly fitted and elevated to prevent water from accumulating.

Maintaining a Clean Pool Area

Keeping your pool area clean can deter horse flies. Ensure the grass around your pool is well-maintained and that chlorine levels are appropriate for your pool. The CDC recommends maintaining a free chlorine concentration of 2 ppm and pH levels at 7.5 or less.

Item Recommended level
Chlorine (ppm) 2
pH 7.5 or less

Also, make sure to remove any debris, such as leaves or dead insects, from the pool and the surrounding area.

Strategically Planting Repellent Plants

Planting repellent plants around your pool can help keep horse flies at bay during the summer months. Several plants are known for their fly-repellent properties:

  • Lavender
  • Marigolds
  • Citronella

Planting these around your pool creates a natural barrier that helps deter horse flies.

By following these simple steps, you can create a more enjoyable swimming pool environment for you and your guests, free of pesky horse flies.

Using Natural Repellents

Essential Oils

Several essential oils can be used as natural repellents to keep horse flies away from your pool area:

  • Citronella oil: A popular insect repellant, derived from the leaves and stems of various species of Cymbopogon plants.
  • Lavender oil: Known for its soothing scent, it also repels insects like horse flies.
  • Eucalyptus oil: It has a strong scent that insects find overwhelming.
  • Tea tree oil: Another effective insect repellent, this oil is derived from the Melaleuca alternifolia plant.
  • Cedar oil: It has a woodsy aroma that insects dislike.
  • Peppermint oil: The cooling scent repels many insects, including horse flies.
  • Basil oil: This herb’s potent aroma can ward off various pests.

Add any of these essential oils to a spray bottle with water, and apply it around the pool area. Be cautious about applying oils directly to your skin, as they may cause irritation.

Citronella Candles

Citronella candles are an easy and effective way to keep horse flies at bay. They release the scent of citronella oil when burned, which repels insects naturally.


  • Affordable
  • Easy to use
  • Pleasant scent


  • Need to be regularly replaced
  • Limited range
  • May not work in windy conditions

Place citronella candles or lamps around the pool to create a barrier that horse flies are less likely to cross.

CO2 Traps

Horse flies are attracted to carbon dioxide (CO2), which they associate with the presence of a host. CO2 traps take advantage of this by emitting CO2 to lure and trap the flies.


  • Attracts horse flies from a distance
  • Traps flies for easy disposal
  • Can be reusable or disposable


  • Range: Varies depending on trap size and design
  • Placement: Position the traps around the perimeter of the pool area
  • Maintenance: Check and empty traps regularly

Compare the effectiveness of these natural repellents in the table below:

Method Cost Ease of Use Range Effectiveness
Essential Oils Low Medium Small Moderate
Citronella Candles Low High Small Moderate
CO2 Traps Medium Medium Large High

Using natural repellents such as essential oils, citronella candles, and CO2 traps can help keep horse flies away from your pool area. Choose the method that best fits your needs and budget to help create a more enjoyable swimming experience.

Dealing with Horse Fly Bites

Taking Immediate Action

  • Clean the bite: Wash the area with soap and water to reduce the risk of infection.
  • Apply ice: Place a cold pack on the bite to ease the pain and swelling.

Recognizing Allergic Reactions

It is important to know the signs of an allergic reaction to horse fly bites, as it may require medical attention. Here are some symptoms to watch for:

  • Difficulty breathing
  • Swelling of the face, lips, or tongue
  • Rapid heartbeat

In case of an allergic reaction, seek immediate medical help.

Painful Bites and Tularemia

Horse fly bites can be extremely painful and may transmit tularemia, a bacterial infection. Here are some common symptoms of tularemia:

  • Fever
  • Chills
  • Headache

Be mindful of these symptoms and consult a doctor if they occur after a horse fly bite.

Comparison Table: Immediate Action vs Allergic Reaction

Immediate Action Allergic Reaction
Clean the bite Difficulty breathing
Apply ice Swelling of the face
Rapid heartbeat

Remember, it’s essential to take proper care of horse fly bites and be aware of the signs of an allergic reaction to ensure your safety and wellbeing.

Addressing Infestations

Using Bug Zappers and Insecticides

Bug zappers attract and kill flies using ultraviolet light. Here are some pros and cons:


  • Effective for small areas
  • Easy to install


  • Requires electricity
  • May kill beneficial insects

Insecticides help control the horse fly population. Common ones include permethrins and cydectins. Consider:

  • Applying near stables, cattle, and rivers for better results
  • Always following the manufacturer’s instructions for safe use

When to Call an Exterminator

If the infestation persists, despite using bug zappers and insecticides, it’s time to call an exterminator. They can assess the situation and provide appropriate solutions.

Comparison Table

Method Good For Stables Rivers & Ponds Prevention Effort Required
Bug Zappers Yes No Yes Low
Insecticides Yes Limited Yes Medium
Professional Exterminator Case by Case Case by Case Varies Depends

Additionally, using DEET and other insect repellents can help protect people from horse flies, especially when near infested areas like ponds and rivers.

Understanding Horse Fly Behavior

Attracting and Reproducing Factors

Horse flies are attracted to heat, carbon dioxide, and movement. They are particularly drawn to warm-blooded mammals like horses and humans. Factors that attract horse flies include:

  • Heat: They prefer warm environments and are more active during hotter seasons.
  • Carbon dioxide: Horse flies detect exhaled carbon dioxide from mammals, which helps them locate their prey.
  • Movement: The flies are visually drawn to moving objects, such as a person swimming or a horse running.

Horse flies lay their eggs in moist soil, often near water or in damp, shady areas like bushes. The larvae feed on organic matter and pollen before migrating to dry soil to pupate.

Hunting Methods

Being visual hunters, horse flies rely on their compound eyes to locate prey. Here are some of their hunting methods:

  • Warm-blooded mammals: Horse flies prefer to target large animals like horses, but they will also bite humans if the opportunity arises.
  • Detection: They use visual cues and chemical sensibility to find their prey.

Comparison of Horse Fly Hunting Methods

Hunting Method Target Detection Method
Warm-blooded mammals Horses, humans Visual, chemical
Visual cues Movement, CO2 Compound eyes

Although there are no known specific smells that repel horse flies, some people try using garlic or special repellents to reduce their presence. It’s important to be aware of the factors that attract horse flies and take measures to minimize them around your pool.

Reader Emails

Over the years, our website, 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 – Four Lined Horse Fly from the UK


Subject: What’s that bug
Location: Oxfordshire
August 10, 2015 2:27 pm
Hi Bugman
I captured this beauty in Oxfordshire UK and have been struggling to identify it. Can you help ?
Signature: Gordon Sheret

Four Lined Horse Fly
Four Lined Horse Fly

Dear Gordon,
We immediately recognized your fly as a male Horse Fly in the family Tabanidae, and our search for its species identity led us to the Influential Points:  How to Catch Horse-Flies page and an image identified as
Atylotus rusticus (scroll down) with this information:  “As well as catching vast numbers of the commoner non-man-biting species (in particular Tabanus bromius), we have found host-seeking females of the very rare and local Atylotus rusticus both within and somewhat outside its usual haunts.”  An image on Nature Photo has convinced us that this is in fact a male Atylotus rusticus.

Letter 2 – Female Horse Fly trapped in web


Subject: Flying striped bodied moth?
Location: Central KY
August 12, 2015 1:53 pm
A big bug was caught in an old web across our glass door. We watched all day as it struggled to get free. I took pictures so I could look it up. We are new to central KY, USA and I have never seen this bug in my life (I come from northern IN).
The wings were clear except for black lines. The body was large, round and striped a yellow and dark brown. A furry head topped it off with a hose type nose and large ovalish eyes. It was quite a specimen!
P.S. It eventually freed itself.
Signature: V

Horse Fly
Horse Fly

Dear V,
One can tell by the spacing between the eyes that this Horse Fly is a female.  Female Horse Flies bite and suck blood from vertebrates, especially mammals, while male Horse Flies do not bite and feed on nectar from flowers.  Based on matching images on BugGuide, we believe we have correctly identified your Horse Fly as
Tabanus sulcifrons.

Horse Fly
Horse Fly

Wow! Thank you for taking the time to reply!
I had the feeling it was a biting type of insect and told my son so.
I am so grateful for your letter!
Bless you,

Letter 3 – Female Western Horse Fly


Subject: Black Moth?
Location: Bay Area, California
August 20, 2015 10:57 am
Just found this moth like creature in my garden this morning (8/19/15) in Fremont, California, zip code 94536. What is it?
Signature: Elizabeth Cerutti

Female Western Horse Fly
Female Western Horse Fly

Wow Elizabeth,
This is one gorgeous image of a female Western Horse Fly,
Tabanus punctifer, who can be easily distinguished from her sexually dimorphic mate by the spacing between her eyes and the color and pattern of the white hair on her thorax.  According to BugGuide:
“From Middlekauff & Lane:
Female: A large, dark-colored horse fly. Easily recognized by the following characteristics: mesonotum covered with creamy hair over a dark reddish background: remainder of thorax dark brown, with concolorous hair: wings brown, paler posteriorly, the cross-veins and furcation distinctly margined with brown; legs black, except basal third of fore tibiae, which are creamy white with long white hair; abdomen black.
Male: Color as in female except that the white of the mesothorax is confined to a lateral band and the outer margin of the scutellum.”
The pastel colors of the succulent plant act as a perfect background for this striking fly.  Female Horse Flies are blood suckers that feed on warm blooded animals, and many species are not at all opposed to sucking human blood.

Wow, thanks for such a quick, complete and descriptive answer!  I had no idea it was in the fly family, and a dreaded horse fly at that. When I was growing up on Long Island, NY, we used to try and dodge horse flies in the swimming pool in the summer.  They were so smart, they used to hover right above and wait for us to surface for air.  Hell of a welt.  This one today in the garden was easily an inch long.
Thank you, again.
Best regards,

When we were putting together our response for you, we searched our archives for an image of a male Western Horse Fly to no avail.  Should you happen to see one, please take an image and send it to us.  Here is a BugGuide image of a male Western Horse Fly.

Letter 4 – Female Western Horse Fly


Subject: Beetle Moth Fly Thing
Location: Colorado
June 20, 2017 12:23 am
I came across this bug when I was walking my dog in a field and I’ve never seen anything like it before. It’s summer here and the bug was a little over an inch long. Any ideas??
Signature: Curious

Female Western Horse Fly

Dear Curious,
This is a female Western Horse Fly, identified by the gray thorax and the space between her eyes.  Only female Horse Flies are blood suckers, and though humans are not a normal host, a hungry opportunistic female Western Horse Fly might bite a person if no livestock are available.


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. 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.

    View all posts
  • 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.

    View all posts

2 thoughts on “How to Keep Horse Flies Away from Your Pool: Simple and Effective Tips”

Leave a Comment