You get botfly maggots through mosquito bites, not from the botfly itself. The human botfly (Dermatobia hominis) uses a remarkably indirect strategy: it catches a mosquito, glues its eggs to the mosquito’s body, and then releases it. When that mosquito lands on you to feed, your body heat triggers the eggs to hatch, and the tiny larvae crawl off the mosquito and burrow into your skin through the bite wound.
How the Botfly Uses Mosquitoes as Carriers
The adult botfly never touches you. Instead, the female botfly captures a blood-feeding insect, usually a mosquito, and attaches up to 30 eggs to its body with a natural adhesive. The eggs ride along on the mosquito, fully intact, until it lands on a warm-blooded host for a blood meal.
The rise in temperature from your skin is the trigger. As the mosquito feeds, that warmth causes the botfly eggs to hatch within moments. The newly emerged larvae are tiny enough to slip through the mosquito’s bite wound or simply penetrate the skin on their own. You won’t feel them enter. In some cases, the female botfly skips the mosquito entirely and lays eggs on plant leaves. If you brush against those leaves, the larvae can transfer to your skin the same way.
Where Botfly Infestations Happen
Human botfly infestations occur almost exclusively in Central and South America, particularly in tropical and subtropical forested areas where both the botfly and its mosquito carriers thrive. Travelers returning from countries like Belize, Costa Rica, Brazil, and Peru account for the vast majority of cases seen in North American and European clinics. If you haven’t traveled to these regions, a botfly infestation is extremely unlikely.
What It Feels Like
Once a larva is under your skin, it creates a firm, raised bump that looks similar to a boil or an insect bite that won’t heal. The key difference is a small central pore, a tiny opening the larva uses to breathe and expel waste. You may notice occasional sharp, stinging pain at the site, and some people report feeling the larva move beneath the skin. The movement is subtle but distinctive, and it’s often the symptom that prompts people to seek medical help.
The bump grows over time as the larva feeds on soft tissue beneath the skin. Left alone, the larva will develop in the layer just below the skin surface for 5 to 12 weeks, eventually reaching 18 to 24 millimeters in length, roughly the size of a large peanut. At the end of that period, the mature larva pushes itself out through the skin opening, drops to the ground, and burrows into soil to continue its life cycle. The infestation is self-limiting: the larva will always leave on its own eventually.
How Botfly Larvae Are Removed
Most people understandably don’t want to wait several weeks for a maggot to finish growing inside them. The most common removal approach takes advantage of the larva’s need to breathe. Covering the skin opening with petroleum jelly, a strip of adhesive tape, nail polish, or even a piece of raw bacon cuts off its air supply. Starved of oxygen, the larva will either migrate toward the surface or partially emerge from the pore, making it easier to pull out with tweezers or gentle lateral pressure.
If the larva doesn’t cooperate, a doctor can make a small incision under local anesthesia and extract it directly. The important thing during any removal is to get the larva out intact. If it ruptures, the remaining fragments can trigger a stronger inflammatory reaction in the surrounding tissue. After a clean extraction, the wound typically heals on its own without complications.
How to Prevent Botfly Exposure
Since botflies reach you through mosquito bites, prevention comes down to avoiding mosquito bites in endemic areas. DEET-based repellents are the most studied option, with effectiveness peaking at a concentration around 50%. Products with less than 10% active ingredient offer only one to two hours of protection, so higher-concentration formulas are worth using if you’re spending extended time outdoors in tropical forests.
Treating clothing, hats, and mosquito nets with 0.5% permethrin adds another layer of defense. Permethrin both repels and kills mosquitoes on contact, but it should only be applied to fabric, never directly to skin. Wearing long sleeves, long pants, and closed shoes, and tucking shirts in and pants into socks, further reduces the amount of exposed skin available for a mosquito to land on. These are the same precautions used against mosquito-borne diseases like dengue and malaria, so following them protects against multiple risks at once.