"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

December 22, 2010

December 22 - Hypoderma tarandi

The warble fly is a nasty parasite which really gets under the skin of Santa's reindeer. Hypoderma tarandi is a pest known to afflict most reindeer populations and it has a life cycle rather similar to the human bot fly. The adult flies lay eggs on the skin of reindeer, and hundreds of eggs can be found in the hide of a single deer. When the egg hatches, the maggot penetrates the skin and burrows under the subcutaneous layer where it proceeds to grow by feeding on host tissue. The maggot can grow up to 2.5 cm long (about an inch) and each deer can be infected with anything from 50 to 300 of such maggots, with some less fortunate individuals hosting 1000 fat maggots under their skin! Ouch -that's going to hurt when Santa hooks them up to their harnesses.

Contributed by Tommy Leung. Photo by Arne Nilssen.


  1. Very interesting. I have an old reindeer hide my parents bought many years ago at Norway. There are countless little holes in the underside of the hide, which are very probably a result of infestation with Hypoderma tarandi maggots.

  2. Yes, very interesting. Why does H. tarandi cause dermal infection in reindeer and caribou but ocular infection in humans?

  3. Not too sure - some author had suggested that when H. tarandi oviposit on humans, they lay the eggs on the hair of the eyebrows or eyelids, and the hatched larvae end up crawling into the eye after they hatch. Incidentally, there is another botfly - Gedoelstia - is also known on rare occasions cause ocular infection in humans, but they actually infect the muzzle or nostril of their natural host.

  4. They lie eggs on the back of one's head , none of my patients with myiasis seen the fly near their face. You wouldn't allow anyone near your eyes