This flower fly is in the genus Eristalis. Adult flies in this genus look like honey bees and are a very common pollinator. They are typically found on flowers. The larva is also called the rat-tailed maggot because it is aquatic and breathes through a long, snorkel-like tube.
Species: Eristalis sp. (probably arbustorum)
Photograph: © 2009 RKD Peterson
Date of Photograph: 4 September 2009
Location: Montana, Gallatin Co. (45o43'41" N 111o08'11" W)