The human bot fly is native to Central and South America. The fly is not known to transmit disease-causing pathogens, but the larvae of Dermatobia hominis will infest the skin of mammals and live out the larval stage in the subcutaneous layer, causing painful pustules that secrete fluids.

Botflies are parasitic organisms and some lay their eggs in mammals. Like human mammals. One type of botfly latches onto mosquitoes mid-flight, attaching their eggs to the mosquitoes’ stomachs. Then, when a mosquito lands on a human’s skin, the eggs burrow into the tiny wound left by the mosquito bite.

Bot flies comprise the family Cuterebridae, and are parasites that attack mammals. Their larvae live inside living mammals. Our most common bot fly is Cuterebra fontinella, reported to occur in most of the continental US (except Alaska), plus southern Canada and Northeastern Mexico.

Most human cases of myiasis are caused the families Oestridae (bot flies), Sarcophagidae (flesh flies), Calliphoridae (blow flies), and Muscidae (house flies). Myiasis caused by endemic Cuterebra species in the US and Canada is rare, with approximately 60 cases reported in the past 70 years [1].

Patients with botfly infestation often describe feeling movement under the skin as the larva feeds and grows, but it does not travel in the body. Once mature, the larva drops to the ground and pupates in soil. Signs and symptoms include a hard, raised lesion and localized erythema, pain, and edema.

But you can also take the “prevention is the best cure” route by spraying your horse with insect spray to deter bot flies from landing on your horse, using a fly sheet, and scraping the bot fly eggs off every day with a bot egg knife or grooming stone.

The easiest and most effective way to remove botfly larvae is to apply petroleum jelly over the location, which prevents air from reaching the larva, suffocating it. It can then be removed with tweezers safely after a day.

The migration of bot larvae under the skin in mucous membranes causes lesions that may provide openings for infection. Flies also carry diseases that can seriously harm your horse’s health and performance. Without treatment, bots can cause severe damage in the stomach and intestine of your horse.

The best prevention is to keep pets inside. This may work well for some cats, but we know this just isn’t realistic for dogs in Castle Rock! As a deterrent, you can apply a topical mosquito spray to your dog as long as it’s approved for use on animals.

Cuterebra is a common fly in North America. The best prevention is to keep your dog from hunting rodents. When this is impossible and if you live in an area with numerous rodents, rabbits or other small mammals, you should closely inspect your dog regularly for any signs of warbles.

For dogs, topical insect repellant, such as those that contain Fipronil (Frontline) or collars impregnated with Amitraz can help. I used Fipronil to kill many ectoparasites, including fleas, ticks, but not adult bot flies. Externally located eggs and larvae that contact the product on a pet’s skin or coat will die.

Carlton’s scalp had become home to a human botfly larva, a spiny parasitic maggot that digs into living human flesh, feeds on the inflamed tissue surrounding it, and grows to more than an inch long.

Pelodera dermatitis is a rare skin worm infestation that causes a short-term skin infection. The condition is caused when larvae of roundworms known as Pelodera strongyloides invade the skin. These larvae are widespread in decaying organic matter (such as damp hay) and on or near the surface of moist soil.