Readers’ wildlife photos: The horrors of the human botfly

September 23, 2025 • 8:30 am

I have recounted previously how, when visiting Costa Rica as a graduate student, I got a human botfly larva (Dermtobia hominis) in my head, and, over the next two months, let it grow between my scalp and my skull until it emerged.

My story was the subject of a Science Friday segment on NPR that you can hear by clicking below. Press “listen”; my segment begins at 43:38 and lasts 12 minutes. I think they did a fantastic job, even interviewing my girlfriend at the time, who was present when the botfly larva emerged from my head.

And below is a great short video of the natural history of this fly produced by my Harvard colleague Piotr Naskrecki. It shows a botfly emerging from a human arm. Note how amazing this creature is: the fly larva not only produces an antibiotic to prevent it from being attacked by microbes while it’s gestating, but also a painkiller  that makes its exist painless (if a host felt it emerging, it might slap and kill the larva). Evolution is amazing!

h/t: Sally, Sarah

14 thoughts on “Readers’ wildlife photos: The horrors of the human botfly

  1. I’m admittedly more interested in parasitic hymenoptera than I am in parasitic diptera,* but the esteemed Piotr Naskrecki is an absolute hero for being the first to consciously allow and document one of our little parasitic friends to grow and emerge within its host, namely himself.

    That he is inspiring others to follow his example to give our parasitic friends the space and love they require is nothing less than amazing. My hat is off and I am kneeling.

    *it’s interesting how hymenoptera never managed to jump to tetrapods as hosts, but diptera did. One assumes the difference in nutritional pathways to have something to do with it (the relevant diptera lineage started with consuming carrion and adapted from there, whereas hymenoptera always stuck to nectar and living hosts), although the existence of carrion bees may give us hope that maybe some day, hymenoptera can likewise expand its host selection to include mammals

    1. I think any curious biologist would have done the same. I raised one to adulthood in the mid 1980s….While it was a larva it was a fun thing to show at parties, as the breathing tube rhythmically poked in and out of the little hole in my arm.

  2. This is so creepy that I couldn’t stop laughing. (Laughing kept me from wretching.)

    Supposedly, the Inuit ate botfly larvae. And it’s debatable whether botflies are kosher or not. https://en.wikipedia.org/wiki/Botfly has the story.

    So kind of you to contribute to the next generation of botflies—and to the pursuit of science!

    1. There is an old movie where Anthony Quinn plays an Eskimo. In one scene he becomes extremely offended when the explorer he encounters refuses his offering of maggots. The only line I remember from that movie is Quinn shouting “But these worms are fresh!”

        1. I’ve heard that Manfred Mann song on the radio many times but did not know Dylan wrote it – thanks! I always assumed that lyric referred to the movie, which is called The Savage Innocents. Wikipedia confirms this: “Dylan is widely believed to have derived the title character from actor Anthony Quinn’s role as an Eskimo in the 1960 movie The Savage Innocents.[5] “

          1. Other Manfred covers perhaps more famous than the originals: “Blinded by the Light” (Springsteen), “I Came for You” (Springsteen), “Father of Day, Father of Night” (Dylan), “Spirit(s) in the Night” (Springsteen). They have also covered other Dylan songs, but other versions (Dylan’s or others’) are more famous.

  3. Cool natural history video. I, too, got a botfly from Belize. Unfortunately, I was not aware of the use of a venom extractor, and ended up trying to squeeze the larva from its warble. It died, and I ended up getting a blood infection that luckily cleared up with antibiotics. So, be careful if you get a botfly; perhaps I should have let it mature.

  4. This blows my mind. I’m curious how in the world Radio Lab found you or was it the other way around… did you take the story to them? Lou Jost (reply to comment #2) says, “Any curious biologist would have done the same”… Really? Good gawd. If you say so. I couldn’t believe my ears listening to that. That’s dedication, for sure. No way! And I did not watch the 2nd video. Wow. I must be a wimp.

    1. Check out Comment 5. If they are big before being detected, it really is probably best to let it live. I asked my doctor about it when I first saw mine, and he agreed with me that it is safe to keep it alive inside my arm, and extraction might have caused an infection.

      I did remove all botflies that I got later in life. One fly-child was enough.

      1. I know, Lou, but the “ick factor” is just too much for me. As I said, I’m a wimp. I couldn’t stomach it. I’d have to be locked up and sedated, ha ha.

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