It strongly resembles the house fly but is in a different family, the Sarcophagidae, or flesh-flies.

In early summer it emerges from pupae in the ground and seeks out forest tent caterpillar cocoons, where it deposits live larvae which bore into the cocoons and feed on the pupating insects, killing them.

Eventually the fly maggots drop to the ground and pupate and go dormant over the winter.

The friendly fly can be a nuisance, but they don't bite, nor do they spread disease.

This article related to members of the muscomorph flies superfamily Oestroidea is a stub.