Some of the common names of the small bee-like flies shown in Figure 1 include corn fly, hover fly, helicopter fly, flower fly, and sweat bee. Each name fits some aspect of the insect’s appearance, behavior, or hangout. These convincing bee mimics are persistent, darting, hovering, and landing on leaves, flowers, and people. Females lay eggs on leaves infested with aphids and feed in nectar for energy. As true flies, they can neither sting nor bite. However, they look threatening and defy attempts to be shooed away.
Hover fly larvae are important aphid predators. They crawl over the foliage of infested plants grabbing and consuming aphids with their paired mouth hooks. A hover fly larva may consume 20 to 30 aphids a day; over 200 during its lifetime. The teardrop-shaped pupae are attached to the leaf surface. These beneficial insects may be heavily parasitized by small wasps.
Lee Townsend, Extension Entomologist