Very common on eastern Long Island. They're in rabbits, deer and woodchuck. A give away for Woodchuck holes you can see the flies circling over the holes in early spring.
Haven't seen "wolves" since I was a kid, maybe 50 or so years ago. They were in/on kittens at my cousins egg farm. Also saw them around that time in/on rabbits.
Nasty looking and pitiful for the creatures that have them.