The human bot fly (Dermatobia hominis) belongs to the insect order Diptera, family Cuterebridae. The adult is a stout-bodied, hairy fly native to Central and South America. In fact, the above larval hitchhiker was "picked up" in Costa Rica. The egg-laden adult female fly temporarily captures a mosquito and attaches her eggs to its body. This encounter presumably occurs during the hours of dusk or later. When the mosquito lands on the warm body of a human for its blood meal, the bot fly eggs hatch and one or more pear-shaped larvae (maggots) fall to the skin surface. The larva bores into the skin and leaves a small "breathing pore."

When it has penetrated the epidermal and dermal layers of the skin, it is firmly held in place by anal hooks and rows of barbs on its body (see image to the left). It takes about five to ten weeks for the larva to complete its development. During this time it feeds on blood tissue within its subcutaneous burrow.

When mature, it emerges from the breathing pore and drops to the ground where it pupates and gradually transforms into a winged adult through metamorphosis. The adult has nonfunctional mouthparts and does not feed. Its primary purpose is to mate and perpetuate the species by capturing another mosquito. Insects truly have some of the most complex and remarkable life cycles of all the creatures on earth.