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Robber Fly
(John Obermeyer, Purdue University)
Common Name: Robber Fly

Order: Diptera

Family: Asilidae

Pest Status: Robber flies feed on other insects, but are not relied upon for biological control because they are excellent fliers and seldom stay in one place for long. They can deliver a painful bite if mishandled.

Appearance: Adults vary in body length (3/8 to 11/8-inch long) and appearance. Most species are gray to black, hairy-bodied, and have long, narrow, tapering abdomens. The adult has a deep depression between the large eyes.

Life Cycle: Females deposit their eggs on low-lying plants or in the soil. The larvae live in the soil or in decaying organic materials while preying on eggs, larvae or other soft-bodied insects. They overwinter as larvae, pupate and emerge as adults in the springtime. Development time ranges from one to three years, depending on environmental conditions.

Where to Collect: These flies are often observed on stems of plants, on the ground, or flying low.