Description: Adults (flies) feed on nectar in flowers, while the larvae (maggots) are voracious predators of aphids. Adults often mimic the color patterns of wasps and bees (LINK TO LOOK-A-LIKES), presumably to gain protection from their own predators. However, unlike wasps and bees, these flies are incapable of stinging and are totally harmless..
Identification: Rollover pictures with mouse for tips on how to identify these predators. Adults: These flies live up to their names, and often spend much of their flight time hovering, unlike bees and wasps which have more directionality in their flight patterns. When they alight on a plant, notice they only have 2 wings (as opposed to 4 in wasps and bees) (click here to compare). Like all flies, their hind wings are greatly reduced (named halteres), and are used to balance them in flight. These flies also have very small antennae, as opposed to the long, often “elbowed” antennae in wasps and bees (click here to compare). Their eyes are often larger than those of wasps and bees, and may look like they wrap around the head (click here to compare). Larvae: As with all flies these larvae are maggots. They may be camoflaged and blend in with their surroundings. The larvae have hooks for jaws that they use to consume aphids.
Value in Pest Management: Hover flies are valuable natural controls and undoubtedly contribute to population regulation of aphids. Conservation biological control efforts have in some cases focused on providing nectar-producing plants (such as alyssum) preferred by hover flies to enhance their populations in adjacent crop fields. They are not sold commercially.
Origin and Distribution: Native, throughout eastern North America (http://www.discoverlife.org/mp/20q?search=Syrphidae).
For More Information: (LINKS)