It’s been a good season so far for grouse hunters, but it may also be a good season for an unusual fly that parasitizes grouse and that can bite humans when they come in contact with the birds they’ve shot. We’ve had reports of this fly suddenly appearing when hunters have been cleaning grouse shot in northern St. Louis County.
They’re called louse flies and they’re from a family of parasitic flies known as hippoboscids. Each species specializes in parasitizing a specific bird or mammal and there is a species known as a grouse louse fly, which targets ruffed and other species of grouse.
Various hunting forums, mostly in Manitoba, have made reference to these flies and, invariably, they tend to leave hunters a bit disturbed. The flies are about the size of a deer fly, but they are narrower and very flat (almost like a roach) which is typical of parasitic insects. They’re also hard to kill. A swat that would normally crush most other flies, is barely noticeable to a grouse louse.
One hunter who had shot several grouse up near Nett Lake reported being bit by one of the flies, but he fortunately didn’t react. He said he hadn’t seen such an insect before, but had assumed they had come off the grouse. The good news is the presence of the flies doesn’t affect the meat of the birds at all. Those breasts will still cook up nice and tender in the fry pan.