My Botfly, Myself

When I was in my mid-twenties, I visited Costa Rica as an ecotourist. One of the more memorable field experiences was watching a small snake consume a large toad over a period of several hours. I photographed the progression of this feast at a cost of just a few mosquito bites on my head,… or so I thought. As it turned out, the snake and mosquitoes were not the only ones dining that night.

Two weeks after my return home some of the mosquito bites had not gone away. Then one morning, I felt a small movement in the bite on my right temple. Weird. Maybe I imagined it. A while later, more movement. Definitely not my imagination. I looked closely in a mirror. At the center of the bite was a small opening with a snorkel periodically emerging from it! I had read about bot flies but never imagined becoming a host.

Bot flies have an interesting life cycle. The offspring must be deposited on living mammals or birds, but the adults, being large, noisy fliers, chase down quiet-flying mosquitoes and lay their eggs on them to avoid getting swatted. When the mosquitoes get a blood meal, the eggs, in response to the host's body heat, hatch and drop onto the host. Then they burrow into a hair follicle or sweat gland, where they begin feeding. The maggots or “bots” traverse their new home with alternating contractions of rows of hooks that encircle their bodies. As parasites go, they are usually pretty good guests despite dining on your flesh. They are careful to eliminate their waste outside their burrow, which they keep antiseptic. After a few weeks of feeding, they crawl out, drop off their host, and pupate in the soil. Some time later, an adult fly emerges to mate and repeat the cycle.

Botflies-usda

My thoughts alternated between excitement and revulsion. Fearing a highly visible scar, I squeezed the “bite” and the tiny maggot popped out like a zit. So much for that.

The next day, I noticed a now familiar movement in the upper, right rear portion of my head. This area was well concealed by hair and I thought even if this things takes a big hunk of flesh, no one will see it unless I become extraordinarily bald (so far this prognostication has held, if only just barely,…). Could I nurture my guest to pupation? As a male I thought this is probably the only opportunity I will ever have for another organism nourish itself on my living flesh. I imagined the movements of the maggot in my head were analogous to the kicking that pregnant women feel from their developing fetuses. It was thrilling, humbling, and a little alarming to suddenly be a link in the food chain rather than its terminal end.

For the next week or so, I proudly showed off my offspring to anyone who was interested. Most people were horrified but a few understood my motivation. Unfortunately, as the maggot grew it became much more active and painful. An occasional nibble could make my eyes water. Eventually it began waking me if I rolled over on it in my sleep. At that point I decided to end my experiment as a host.

Luckily, one of my housemates was from Brasil where botflies are fairly common and their removal is routine. There they hold a piece of meat over the fly's breathing hole until it begins suffocating and backs out into the meat. Alternatively, they cover the hole with Vaseline and sieze the maggot as it backs out. We tried this latter technique, and as the maggot emerged, my other housemate grabbed its snorkel with tweezers and pulled. It reflexively withdrew deeper into my scalp. A tug of war ensued and the rows of hooks dug into my flesh and felt like a hot poker. The inch long maggot, slowly stretched to over four inches before finally letting go. Note: I got lucky, because if the larva tears apart, whatever remains behind can lead to a nasty infection. As a single drop of blood oozed from my scalp, I preserved the bot in vodka.

As a result of my experience, I became much more interested in parasitology as a discipline within biology, and also began to think a bit more about humanity's place in the world. For several years afterwards, I would occasionally get tingling feelings where the botfly had once dined: A reminder that, to much of life on the planet, we are merely food.

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