Narr: Botflies lay eggs on other insects, called vector hosts, which in turn carry the eggs to other locations.
Narr: When the vector bites a bigger host, like a cow, the eggs sense the new host's body heat and burrow beneath its skin.
Narr: The larvae stay under the skin for months, happily munching away.
Narr: It's a nice, safe spot for the little parasite...but it's not so fun for the unwitting host.
Narr: Especially when that worm takes up residence in an inconvenient location.
Narr: National Geographic photographer Joel Sartore is the proud surrogate parent of a botfly larva.
Narr: He's not quite sure when he became a father—but when you spend that much time with bugs...
Joel: That was one of the stinging ones!
Narr: ...something odd is bound to happen.
Narr: He shot a lot of close ups, but he never thought he'd be this close.
Joel: Oh, man...
NATSOT (subtitled): Ah, it's a big maggot, eh?
NATSOT (subtitled): Here it is.
NATSOT (subtitled): Yes, a maggot...
Narr: Traditional treatments involve covering up the larva's breathing hole so its head emerges, then grabbing it and pulling it out.
Narr: Parasitic larvae like the botfly can live in almost any part of the body...even the scalp.
Narr: This woman, Vanessa, found out the hard way.
Narr: She returned from a trip to Belize carrying a very unwanted souvenir.
Vanessa: Oh God, he saw it!
Narr: A bug...in her head.
Narr: First, she tries to smoke it out...to no avail.
Narr: Next, a high-tech medical remedy—tape over the larva's breathing hole...and the worm emerges.
Vanessa: It's kind of stuck.
Narr: Sort of.
Narr: Yes, that was living in a woman's scalp.
Narr: If they never encounter tape and a pair of tweezers, the botfly babies eventually come out on their own.
Narr: If allowed to eat their fill, the larva will burrow out to pupate.
Narr: But this is one baby that no one would want to keep...
Vanessa: Ow! Oh, God, that hurts.
Narr: ...even the botfly.
