These beetles come out in early spring, fly low and erratically close to the ground, and in general look like bumblebees. But they are not. They are scarab beetles in the Genera with the delightful name, Euphoria! They are relatively large, about 12 mm, up to 16mm according to Bug Guide. Also according to the latter, the adults feed on nectar and pollen, as well as tree sap and the juice of rotting fruits.
I first saw one of these in early spring a few years ago and thought that I was looking at a bumblebee, but when it buzzed by me again (and it does buzz, just like a bee) I saw it was a funny, fat beetle. Unfortunately, it vanished and I never saw any again until today when there were several flying around near a colony of ground nesting bees.
Photo taken in Dunrobin.