Why does Rudolph have a red nose?

Rudolph the Red-Nosed Reindeer is a Christmas icon, immortalised in books, songs and films.

But the cause of this beloved cervid’s crimson nose has often been the subject of festive debate.

In the video above, our fly expert Dr Erica McAlister hints at why Rudolph’s nose might glow so bright. Read on for a closer look at the culprits.

Meet the snot bot

Reindeer sometimes suffer with symptoms similar to a cold, such as coughing and spluttering – and maybe even that legendary red nose. The cause is not a common cold, however, but an infestation of fly larvae.

‘Snot bots’, as they’re affectionately known, are the culprits. These are flies of the genus Cephenemyia, also known as the deer botflies. The reindeer warble fly, Hypoderma tarandi, is also guilty of infesting cervids.

As adults, these flies are fuzzy in appearance, making them look a little bit like bumblebees. But other than that they’re both insects, appearance may be where the similarities end.

Female deer botflies squirt their larvae up the noses of unsuspecting reindeers. The larvae then crawl down the deer’s throat to live and feed on the tissue there.

After growing a little, it’s time for the larvae to leave, so they begin irritating the deer’s throat. This causes the deer to cough and splutter so much that the offending insects are ejected from their temporary home through the mouth or nose of their host.

It would then, perhaps, be no surprise to see a reindeer with a very shiny nose.