D) All of the above



It happens when the deer are in velvet. Those antlers are full of blood at that time of year. If you ever have the chance to feel the antlers on a pet buck when it is in velvet, It is very hot to the touch because of the blood flow.

This blood does attract insects. The fly larve is probably the most common cause. Sticks, barbed wire fence, ticksand other things can cause damage too.