Bot flies (Order Diptera, Family Cuterebridae)
are large, stout bodied, hairy flies that resemble bumblebees. The botfly
egg is deposited by a mosquito or sometimes by another insect. The larva
grows in the host's body until it is fairly large. The botfly larva can
easily be killed by taking away its air supply -- by putting vaseline
or similar on the skin where the lump is, but then you still have to extract
the larva. Adult botflies have nonfunctional mouthparts and do not feed.
Larvae of this species parasitize wild and domestic rabbits. Females deposit
their eggs in or near the entrance of their host's burrow. Bot fly larvae
penetrate their host through the skin or natural body openings after hatching.
The larvae form a tumor (called a warble) in the subdermal zones of their
host and remain at this location until larval development is complete.
Larval development varies among species, ranging from 20 to 60 days. Before
pupating, the larvae leave the host's skin and drop to the soil.
Generally, the host is not severely damaged
by this parasite. The majority of the injury occurs when the larvae exit
the host through the warble. Parasitism by the botfly does not affect
the edibility of the rabbit (assuming you eat rabbit), generally the area
adjacent to the warble is trimmed away, and the rest of the rabbit is
suitable to eat.
Is there such a thing as a human bot fly? Yes, we're sorry to say there
is. Called the torsalo, Dermatobia hominis, occurs in Mexico and Central
America. Fortunately, getting one is an extremely unlikely occurrence
for the average visitor.
One of the really cool things about this insect is that
it lays its eggs on a mosquito and the eggs hatch when the mosquito feeds
on a host. Do humans get warbles? Yes, (are you disgusted yet)?
While the maggot feeds on its host (you) it has to have a hole in the
skin so it can continue to breath. It takes about 6 weeks to complete
development on its host. There are stories of entomologists rearing torsalos
on themselves in order to get a good specimen of an adult (which are rarely
captured), but we regard this as taking your profession a little too far.