The human botfly is a small, hairy fly found in Central and South America. Unique among skin parasites, the botfly itself doesn’t actually burrow under the skin. Instead, it lays its eggs on mosquitoes, ticks or other flies. When a person is bitten by one of these insects, the eggs are triggered to hatch into maggots by a human’s body heat
Botfly maggots burrow just under the skin and leave a hole through which to breathe while they feed off blood and tissue. The burrows look like large white boils, which swell under the skin and cause intense pain. Maggots also secrete a sort of antibiotic to ward off infection while they feed.
As the maggot grows, it swells under the skin and causes intense pain. Victims may also feel it biting and wriggling around as it feeds. If not removed or otherwise disturbed, the maggot will drop out of its hole after six to eight weeks so it can pupate.