Veronica Yurchak, Vegetable Specialist, UMD; vjohnso4@umd.edu
The goal of this series is to increase awareness and knowledge of beneficial insects in cropping systems to help differentiate them from pests of concern. Over the past week I have noticed an abundance of predatory long-legged flies (Family: Dolichopodidae) darting around crop fields and home gardens. Easily recognized by their beautiful metallic coloration and long, slender legs (Figure 1), adult long-legged flies are predators of numerous small pest insects including leaf-miner flies, aphids, thrips, spider mites, whiteflies, and mosquitoes. While relatively little is known about the extent to which long-legged flies reduce pests, their predatory feeding habits and typically high abundance in cropping systems suggest they can be important contributors to the suppression of insect pests. The immature stages typically occur in moist soil and are rarely seen. For many species, the larval stage is also predatory, feeding on springtails and other small invertebrates in the soil. Simple ways to draw in long-legged flies and other natural enemies include increasing the diversity of plants in cropping systems and avoiding the use of broad-spectrum insecticides whenever possible.
Figure 1. A metallic greenish-gold long-legged fly.