"What but design of darkness to appall?/If design should govern in a thing so small."
You're a cheerful Lonely Planet type -- that's your first mistake.
You're travelling around Central America -- that's your second mistake.
You get a bite and ignore it, because gawrsh, the creepy-crawlies were here first! -- that's your third and final mistake.
You are now hosting one of the most gratuitously appalling creatures on this Hell planet: Dermatobia hominis, the Human Botfly. Excessive, pointless sadism is this creature's trademark. At every stage, from egg to larva to adult, the creature is a living sermon on the horror that is organic life. If Sunday services were replaced with lectures on the life cycle of Dermatobia h., IQ ratings and suicides would both rise sharply.
The adult botfly looks like a 25th century alien weapon, with huge compound eyes, a massive head, and a dwarfish, metallic body. The adult's job is to plant its eggs in a mammalian host. But here, as in every stage of its life, the botfly always does things in the most gross and complicated way imaginable. It's Alien with a sense of humor.
So instead of simply landing and shitting out an egg on the victim on her own, the adult female botfly hunts for a mosquito. The mosquito is going to play Stork for her, delivering her baby to its new host.
Mother botfly hunts the tropical night until she finds a mosquito. And here again, she does her task with gratuitous elaboration, capturing the poor mosquito in mid-air and holding it still while she glues her eggs to the mosquito's exoskeleton. Then she flies away, and the confused mosquito goes back to her relatively innocent career of sucking blood and giving people malaria and dengue fever. (One sign of the botfly's Satanic greatness is the way it makes the mosquito, humanity's most lethal enemy, seem sweet by comparison.)
Finding a hot spot on our backpacker's freckly ankle, the mosquito settles in for a nice long suck. But the botfly eggs glued to her body sense the heat of that mammal flesh so near at hand. The eggs break open, and the little larvae, pear-shaped maggots studded with rows of hooks, fall onto the mammal's skin, then quickly chew themselves nice warm dens in that tender hide.
Once the larva has chewed itself a little burrow in your flesh, it expels an antibiotic from anal glands -- not because it worries about your health, but because it doesn't want to share its new home with rivals like fungi or bacteria. Then it slides in, ass first, and locks itself in place with anal hooks. If you try to pull it out now, it will rip in half and die--and so will you, because a hole full of dead larva is gangrene waiting to puff up.
For the next six weeks it slurps your juices, chews your flesh, and gets big and strong. Of course there are wise old native methods of getting rid of botfly larva. And like all wise old Native methods, they're dangerous, disgusting and ineffective. You can smear the sap of a local plant on the hole. It will kill the larva...oh yeah, but then you get an infection and wake up to find the local carpenter sawing your foot off. OK, then you can put a piece of meat over the burrow. Since the larva needs to breathe, it will chew up into the meat and then you can boil it, or fricasee it....Except it doesn't actually need to breathe that much, and most reports say it just ignores the meat.
Then there's the direct action method, where the local healer puts his filthy thumbs on the swollen burrow and gives a big healthy SQUEEEZE! This may not get the larva out, but provides entertainment to the villagers who get to watch -- especially because one of the larva's many skills is the ability to jump six feet. Pop! goes the larva, and where it stops nobody knows. The eXile read an account of a Canadian aid worker -- they're very trusting, Canadians -- who let the locals try this with two larvae which had burrowed into his leg. The first larva popped out on cue, but the second one just dug its anal hooks deeper into his meat...it gets kind of messy after that.