Why is Rudolph's nose red, you might wonder? Could it be that he is infected with Cephenemyia trompe, the reindeer nose bot fly? Like the warble fly, that you met two days ago, these flies lay their eggs on the skin, only in this case, the females seem to prefer the muzzle and nostrils of the reindeer. The larvae typically infect the throat of the deer, growing and developing over the cold winter months. In the spring, the reindeer cough them up and then they pupate and mature into adult flies. The flies seek out new hosts using olfactory cues from reindeer urine and pheromone glands. These are just three of the couple of dozen parasites known to infect reindeer.
Photo by Arne Nilssen.