A buddy of mine recently killed a deer and said he had an important question for me. He had shot a pretty nice 8 point and decided to make a European mount with the skull and antlers. When he went to cut off the buck’s head, he witnessed a number of “grubs” in the deer’s throat. He said, “I’ve been white-tailed deer hunting all my life, but I’ve never seen nothing like that. What is that nasty grub worm doing in the buck’s head, nose and throat?”
To say the least, it was a little unsettling for him to find grubs crawling in his buck’s throat. He continued, “What’s wrong with this deer, and is it safe for me to eat the meat?” Before I gave my friend any definitive answer, I had a few questions of my own. Were these grubs located more or less in the throat, behind the jawbone? “Yes.” How many did you see? “About twenty.” What color were they? “Light-yellow with some brown-ish-ness.” How big were they? “About an inch long and a little fatter than a pencil.”
I then had enough information to assure my friend that his deer had been infected with a common parasite, known as the nasal bot, that hunter sometimes see while whitetail hunting. The “grubs” he discovered are actually the developing larvae of the bot fly (Cephenemyia spp.). These flies are known to infect deer, elk, moose, caribou and bighorn sheep. Taxidermists and deer processors are familiar with bot larvae, since they develop in pouches on either side of the throat at the very base of the tongue.
Although these bots are parasitic, deer seldom exhibit any outward signs of infection, and the presence of bots does not affect the quality of the meat. The adult bot fly resembles a bumblebee in size and coloration. The life cycle begins when bot eggs hatch within the uterus of an adult female fly. The female then finds a deer and sprays these minute larvae in the deer’s nostril
while she is in flight.
The larvae will migrate over the mucous membranes of the upper respiratory tract and eventually into the throat pouches, where they attach themselves to the pouch wall using their oral hooks. Here the larvae will complete their development. When the larvae have fully developed, they release their hold and will drop out or are sneezed out of the deer’s nose.
The larvae will then pupate in the soil for a period of three to six weeks before emerging as an adult fly. Adults mate and the cycle continues. The adults live only about a week and do not have any mouth parts, so they don’t even eat. In the winter this process takes about six months, but in the summer the life cycle is completed in about three months.