What Is A Botfly? (Tips to Identify Botflies)

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Botflies have been called the Aliens of the bug world, burrowing inside a living host, animal or human, to gestate until they burst out of the host’s skin. Except, they don’t actually kill or hurt the host during all the process.

This puts them firmly in the “gross but harmless” category.

Botflies don’t produce any infections in their hosts, don’t cause any harm (other than some swelling around the site), and eventually leave of their own accord to pupate and turn into adult botflies.

If you’ve been hearing a lot about botflies and want to know more about them, or you’re concerned your pets or livestock might have botflies, keep on reading and we’ll tell you all about them.

Reviewed By:
Ed Spicer

Ed has been working in the pest control industry for years helping 1,000's of homeowners navigate the world of insect and rodent management. He manages Pest Strategies now helping homeowners around the world!

Table of Contents

    What Other Names Are Botflies Referred To As?

    Botflies or bot flies (either spelling is correct) are known by the scientific name, Dermatobia Hominis.

    They are mostly a South and Central American pest, so they are also called berne (Brazil), mirunta (Perú), moyocuil (México), mucha (Colombia), torsalo (Central America), and ura (Argentina). Additionally, they are also known as a warble fly, a heel fly, and gadflies.

    Note: Southern California is the only part of North America where botflies are normally found.

    Botflies also attack animals and each one has its own scientific name. For example:

    • Cattle – Hypoderma Bovis
    • Sheep/Goats/Reindeer – Oestrus ovis
    • Horses/Donkeys – Gasterophilus intestinalis (lives in the stomach)

    Other names include cattle grubs (H. lineatum), sometimes known as heel flies.

    Check out the video below for details on how to remove bot fly larvae from human skin.

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    What Are Botflies Commonly Mistaken For?

    Due to their hairy bodies and coloration, botflies are often mistaken for a bumblebee or horsefly. They are, however, very rare in North America. Recent cases of botfly infestation have all been due to people traveling, vacationing, or working in South and Central America.

    Botflies Vs. Mosquitoes

    One of the strangest symbiotic relationships in the world of entomology is the one between botflies and mosquitoes. During its short life, the female botfly will mate, then capture a mosquito in flight, lay eggs on it, and release it unharmed.

    The eggs hatch into the larval stage when the mosquito bites a mammal (including you) and drop off onto the host. They will enter the host through the hole left by the mosquito bite or in the openings around hair follicles.

    The botfly maggot or larvae molts several times during the infestation of the host. In humans, this infestation is known as cutaneous myiasis. Neither the host (human or animal) or the mosquitoes are harmed at any point in the process.

    Read More: How to Get Rid of Mosquitoes

    Botfly Vs. Yellow Fly

    Due to its yellow coloration, the yellow fly, sometimes known as the batlass fly is sometimes mistaken for a botfly. Yellow flies, known in Belize as a doctor fly, are fierce biters.

    They are quite distinct from botflies though since adult botflies don’t have the ability to bite anything. If you’re being bitten without mercy by a furry-looking yellow fly that looks similar to a bumblebee, you might think it’s a botfly but it’s not.

    Botlfy Vs. Horse Fly

    Horseflies are bloodsuckers, just like mosquitoes. They are frequent pests around cattle yards and livestock pens. They can reach sizes of up to 1-1/4 inches in length, much larger than the average botfly.

    If a botfly is in the same area as a horsefly, it could lay its eggs on the bite marks left behind by the horse flies. It is a rare occurrence but it has been known to happen. 

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    What Do Botflies Look Like?

    Adult botflies have large bulbous heads covered with hair. The hair may be different colors, from black and white to reddish-orange. They are true flies, order Diptera, with only one set of wings. They are generally 1/2” to an inch long and have no functioning mouthparts at all.

    The larvae are quite different. They are soft, lumpy ovals about 1-2 centimeters in length with backward-pointing spines all over their body to anchor them in place within their host’s body. They live just under the skin and the only sign of their presence is a boil-like swelling, known as a warble.

    What Do Botflies Eat?

    An adult botfly doesn’t eat anything. In fact, the adults are incapable of it because they don’t have any working or functioning mouthparts. Consequently, once they emerge from their cocoon they only live a few days until they die. They live just long enough to mate and reproduce.

    The botfly larvae, inhabiting their host, live on the decaying tissue and fleshy matter that falls off the host due to the presence of the botflies. At each instar, when they molt and shed their skin, it too begins to decay and they eat it as well, in a form of self-cannibalization.

    Are Botflies Poisonous or Dangerous?

    No, not at all. A botfly infestation doesn’t harm the host. They need a breathing hole in the host’s skin, but once the botfly larvae emerge from the host’s skin, the skin lesion they leave behind heals within a couple of days.

    Furthermore, they don’t transmit diseases or pathogens.

    This happens whether it’s a human botfly or animal botfly. The life cycle and results are the same for both. Bluntly put, botflies are gross but not harmful.

    Read More: How to Get Rid of Flies

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