Nasal bot fly infestation in roe deer

I always say people are missing out not boiling out their trophies themselves… 😆 This post is really a follow up. In my previous post I mentioned a buck I missed with the first shot, but he never ran away, not even looked my direction. He was about 150m away and it was a bit windy and I thought terrain and wind just attenuated the shot or the buck simply could not figure out from where the sound came from. After boiling out the head I found out it actually had severe nasal bot fly infestation. I counted 50 large larvae and most of the nasal cavity and throat was literally blocked by them. It must have been great discomfort for the roebuck, but to be completely honest, neither me nor my father-in-law seen any obvious signs despite watching the animal for 15-20 minutes before the shot.

Nasal bot fly (latin Cephenomyia stimulator) is quite common in some of the areas I stalk. I have never found any in Scottish roe and they are unusual in some other areas, whereas half of the roebucks from a forestry in one particular area would have it. You can sometimes see roe running away from flies, this often would be nasal flies trying to deposit larvae on deer’s nostrils. Larvae would then move further inside. They reach 2-3cm in length and live inside nasal cavity, throat or even inner ear.  From my experience, this would usually be 10-20 larvae, so this was exceptional case of over 50. They cause irritation and breathing difficulty. When a larva reach 2-3cm it would travel down to  nostrils to be sneezed out and the rest of it’s  metamorphosis takes place in soil. A fly would emerge from the soil not deer itself.

It is sometimes possible to see whether a deer is suffering from nasal bot fly infestation. It is quite common for roe deer to shake its head, cough and sneeze. Mat hair, ugly scruffy coat could also nasal bot larvae infestation.

It is not pleasant to see all the warms inside, but this is part of the sport and good to know about. It is not notifiable disease and the carcass in exception of extreme cases of weight loss (apart from head) should be edible and could enter food chain.

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  1. I know how you feel, not very pretty thing.. I suppose they are also in Sweden, but you do not see them as start your buck season quite late? But could be wrong, maybe Sweden is free from nasal flies?


  2. We have Nasal bot fly in moose in Sweden. Wiki, Älgen nässtyngfluga. The first case of nasal bot fly was found in roe in Sweden in 2012.

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