Found in the Burnt Lands Provincial Park. I have only seen this particular sawfly species once, and have not yet found the larvae. According to Dave Smith on Bug Guide, its larval host plant is snowberry (Symphoricarpos), and there were several small snowberry shrubs nearby, although this adult is sitting on a willow.

Not a fly, despite its common name, but a member of the Hymenoptera, bees and wasps.