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Beware The House Of Tabanideae!

October 20, 2016

up close look at a horse fly in South FL

The insect family Tabanidae includes some of the most notorious biting flies in South Florida.  Horse flies, deer flies and yellow flies all belong to the family Tabanidae.  This article lists these infamous biting flies with descriptions including basic characteristics and unique features that could come in handy if you happen to run into one of these nasty little guys.

Horse Flies

Appearance: Horseflies are one of the largest flies in the world, sometime growing to be over an inch in length. Their clear and cloudy wings can more conclusively identify them as horse flies.

Behavior:  Female horseflies opt to bite larger, nonmoving mammals around their legs and bodies; they seldom bite near the head.  If a female horsefly is interrupted while feeding, she will quickly return to bite the same host again so she can finish her meal.

Habitat: They can be found all over the world.  They generally prefer living in places where livestock also live and that have a source of water.  Both livestock and water provide horse flies with sustenance.

Diet: Male and female horseflies differ in their diets.  Males feed on pollen and nectar while females feed on blood from mammals.

Bite:  Female horseflies are responsible for the infamously painful bites.  They have sharp mandibles that resemble serrated steak knifes, which they use to literally cut a hole in your skin so they can get to your blood.  If you were wondering why horsefly bites are so painful, well that’s why.  Horseflies pose serious health risks to livestock because frequent biting can lead to weight loss and lowered milk production in cows.

Activity:  Horseflies thrive during the summer; as the horsefly population grows, so does the likelihood that we will be attacked.  They are less active during the cooler times of day as well as when it is windy outside.

Unique Features: Horsefly larvae are cannibalistic in nature.  In fact, these babies are typically found growing up alone because they’ve eaten all their brothers and sisters!

Deer Flies

Appearance:  They are smaller in size than horseflies.  Their coloration ranges between gray and black, and some have yellow striped patterns that resemble that of a bumblebee.  The dark bands and spots seen on their wings can help to conclusively identify them.

Behavior: Unlike horseflies, deer flies target moving hosts, and they tend to bite higher on the body, usually around the head or neck.

Habitat:  Deer flies prefer a habitat that is sunny with a source of water and prey that is sufficient enough to support breeding and growing.  This could become a serious issue since pools make an ideal habitat for deer flies because they are attracted to the movement of swimmers and the water’s reflective and shining surface, so they are often seen living around swimming pools.

Diet: Their diet is basically the same as that of horseflies: the females feed on blood from mammals and the males feed on pollen and nectar.

Bite:  Just like horseflies, the deer flies use their mandibles to cut the skin open and get to the blood.  They often leave behind a painful wound at the site of the bite.  They pose a health risk because when feeding they can transmit diseases to their prey such as Lyme disease, hog cholera, and anthrax.

Activity: They are active during the summer in areas where the sun is shining; they are the most active during dusk and dawn.  Low temperatures and overcast skies cause inactivity in deer flies.  They usually stay away from heavily shaded areas. 

Unique Features: Unlike horseflies’ cannibalistic young, the larvae of deer flies live together in large groups.

Yellow Flies

Appearance:  They are about the same small size as most deer flies.  Their coloration, as suggested by their name, is always yellow, although the shades of yellow are varied across the species. 

Habitat: Unlike horse and deer flies, they will avoid the harsh rays of sunlight, instead preferring to stay in the shade of wooded areas nearby flowing bodies of water like ponds.  They tend to venture out when the sun is low in the sky, so they are known for biting in the early morning and late afternoon.

Behavior:  Yellow flies are aggressive and persistent when it comes to feeding.  They will choose their prey, and then continually attack the same prey until they are satisfied with their meal.  So it is frightening and painful for a person who is chosen as prey because the yellow flies will follow them around and bite them over and over again until they are not hungry anymore.  

Bite:  Just like the other two flies, the yellow fly bites by using a scissor-like action to cut the skin open in order to get to the blood.  Unlike their relatives, they do not carry nor transmit diseases when they bite. 

Activity:  Seasonally, yellow flies appear in the late spring, especially during May, and their high activity in this time is aggravating to locals until June when their populations dwindle as they begin to die off.  Unfortunately, they experience another surge in population a little later on in the summer during the months of August and September. Most repellents don’t work to keep them away, so it is better to plan outdoor activities in times when you know yellow flies are less active such as going running around mid-day instead of in the morning or scheduling a canoe trip during the month of July instead of August.

Unique Features: Yellow flies are proven to be attracted to dark colors that contrast with the environment.  Recently, new evidence came to light that suggests they may also have a fondness for vibrant blue colors. 

If you have any questions about the biting flies of the family Tabanidae or if you are interested in our pest control services, please call Nozzle Nolen at (888) 685-0376 or click here to schedule your free inspection.


AMCD. "Yellow Flies." Beach Mosquito Control Disrict. South Walton Mosquito Control. Web. 2016. <>.

"Deer Fly." The Virtual Nature Trail at Penn State New Kensington. Pennsylvania State University, 8 Oct. 2013. Web. <>.

Scachetti, Leanna. "Yellow Flies Taking a Bite Out of Summer." News Channel 7, 21 June 2015. Web. 16 Oct. 2016. <>.

Townsend, Lee. "Horse Flies and Deer Flies." Entomology at the University of Kentucky. University of Kentucky, 2016. Web. <>.

Vadnais, Janelle. "15 Interesting Facts about Horseflies | Run, Janelle, Run!" Run Janelle Run!, 25 Apr. 2012. Web. <>.


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