Pupae are grey in colour, hard, and about 15 millimeters in length. They have a shorter, but recognizable, remnant of the larval breathing tube. Details on the remainder of the lifecyle are sketchy. It is thought that adult flies emerge from the pupae after three weeks, then seek overwintering sites. Alternatively, the insect may overwinter in the pupal stage and emerge in the following spring.
Adults feed on nectar and probably serve a minor beneficial role by pollinating flowers.
Drone flies belong to a larger group of flies technically called Syrphidae, with the common name flower flies or hover flies. Drone flies, the adult form of the rat-tailed maggot, may be mistaken for honey bees, which are of similar size and colour and also frequently seen near flowers. However, drone flies have a swift, darting pattern of flight and are often seen hovering. Rat-tailed maggots are harmless to livestock, pets and people. They are considered a pest only because their presence may reduce the aesthetics of livestock facilities.