Submitted to: Growertalks
Publication Type: Trade Journal
Publication Acceptance Date: June 28, 2004
Publication Date: August 2, 2004
Citation: Sensenbach, E.J., Sanderson, J.P., Wraight, S.P. 2004. Hunter flies: good guys in the greenhouse. Growertalks. 68(4):85-86.
Collaborating Cornell University and USDA-ARS researchers were recently alerted to the activities of small predatory flies inhabiting greenhouses in central NY. These insects were considered beneficial, as they were observed feeding on fungus gnats and other flying insect pests. The flies, similar to but smaller than the common house fly, were ultimately identified as Coenosia attenuata, a species originally described from the Old World. Identification of the flies as C. attenuata represented the first reporting of this predator species in North America, and this discovery was published in the 2003 Proceedings of the Entomological Society of Washington. Subsequent surveys revealed the fly's presence in greenhouses across the U.S. (Maine, New York, Illinois and California) and as far north as Ontario, Canada. Flies of the genus Coenosia are commonly referred to as hunter flies; the adults are predators of a broad range of flying insects, including many pests of greenhouse crops such as fungus gnats, shore flies, leaf-miner flies, whiteflies, and leafhoppers. Larval hunter flies are also predatory. Living in soil or other plant potting media, they feed on the larval stages of fungus gnats and likely attack a variety of other soil-dwelling prey. These characteristics suggest considerable potential for biological control. Initial realization of this potential may lie in developing methods to increase the populations of flies already present in the greenhouse. This might be done by providing a stable soil environment where survival of the fly's immature stages is assured.