Confession: I'm kind of obsessed with bot flies. In fact, I've probably watched every single bot fly larvae removal video on YouTube. So I was obviously predisposed to enjoy this short documentary by entomologist Piotr Naskrecki, who became host to three human bot fly (Dermatobia hominis) larvae after he traveled to Belize last year. But even if you're not obsessed, the short documentary that came out of his experience is a fascinating look at the fly's life cycle. (If you're squeamish, though, it's best to heed the warning!)
Naskrecki removed one bot fly larva from his hand because it was painful, but because he had never seen an adult bot fly, he decided to let the other two live, mature, and emerge from his skin. "I figured that being a male, this was my only chance to produce another living, breathing being out of my flesh and blood," he says in the video.
The human bot fly's life cycle works like this: Adults have just a few days to mate, and after that, a female will catch a mosquito, lay her eggs on it, and set it free. When the mosquito lands on a human to feed, the person's body heat causes the eggs to hatch, and the larvae drop onto the skin, taking up residence in the skin for two months. Then they head to the soil to pupate and, after awhile, a grown bot fly will emerge.
It took just about 40 minutes for the larvae to emerge from Naskrecki's skin—which wasn't really painful, he explains, because the larvae actually create a painkiller so that they can escape unnoticed. "In fact, I probably would not have noticed it if I hadn't been waiting for it," he says. The holes in his skin healed in 48 hours; the bot fly didn't emerge from its puparium for more than a month and a half.
"Raising two dipteran children was an interesting experience," Naskrecki writes on his Vimeo page. "It was embarrassing on a few occasions, when both of my arms started bleeding profusely in public; painful at times, to the point of waking me up in the middle of the night; and inconvenient during the last stages of the flies’ development, when I had to tape plastic containers to my arms to make sure that I will not lose the emerging larvae. But other than those minor discomforts it was really not a big deal. ... [It] also made me ponder once again the perplexing element of the human psyche that makes us abhor parasites but revere predators. Why is it that an animal that is actively trying to kill us, such as a lion, gets more respect than one that is only trying to nibble on us a little, without causing much harm?"