Haven't seen a wolf (warble, botfly) on a squirrel, but did have to remove one from a cat's neck. I didn't know what it was at first. It just looked like a round spot of infection with a raised circle of bare skin around it. After trying antibiotics, peroxide etc. on it without effect, I noticed it had turned into an open hole. One day I noticed a grey bumpy object sticking out of it. I thought something had gotten in the hole, so I grabbed ahold of it with a pair of pliers and pulled it out. It turned out to be a spiny worm about as big around as my finger and about an inch and a half long. It had bored a hole into the neck of the cat about three inches long. Nasty looking, but the cat healed quickly.