The human botfly (Dermatobia hominis) is a parasite that uses a unique and unsettling method to reproduce. Unlike other insects that lay eggs directly on a host, the female botfly captures a blood-sucking insect, like a mosquito, and attaches her eggs to its body.
When that mosquito bites a human, the warmth of the skin triggers the botfly eggs to hatch. The microscopic larvae then enter the host’s body, often through the mosquito bite wound or by burrowing directly into the skin.
Symptoms and Development
Once under the skin, the larva creates a raised lesion that looks like a large, persistent pimple or boil. This lesion, known as a furuncle or warble, will have a small central opening called a punctum.
Breathing: The larva keeps this hole open to the air to breathe.
Sensation: The host may feel intermittent sharp pains or a disturbing sensation of movement under the skin.
Growth: The larva feeds on the host’s tissue and will grow for 5 to 12 weeks. Its body is covered in spines that anchor it firmly in place, making removal difficult.
Maturity: If left untreated, the fully-grown larva will eventually emerge from the skin on its own, drop to the ground, and pupate in the soil.
How is a Botfly Larva Removed?
Because of the larva’s anchoring spines, simply squeezing the bump is often ineffective and can cause the larva to rupture. A ruptured larva can lead to a severe inflammatory reaction or a secondary bacterial infection.
Medical professionals and individuals use several common methods for removal:
Occlusion (Suffocation): This is the most common field method. The breathing hole is covered with a thick substance to cut off the larva’s air supply.
Substances used: Petroleum jelly (Vaseline), bacon fat, or heavy tape.
Process: After several hours, the suffocating larva may emerge on its own or move close enough to the surface to be gripped with forceps and carefully pulled out.
Surgical Extraction: A doctor can administer a local anesthetic, make a small surgical incision, and remove the larva with forceps. This is the quickest and most reliable method to ensure the entire parasite is removed.
Venom Extractor: In some cases, a snakebite suction device can be placed over the hole to draw the larva out with negative pressure.
After removal, the wound must be thoroughly cleaned and treated with antibiotics to prevent infection.