Hunter flies (Coenosia attenuata) are being found more often on sticky cards in greenhouses. This grayish, predatory fly is similar in appearance, but smaller, than the common housefly. Leanne Pundt, Univ. of Conn. extension horticulture and greenhouse IPM specialist, and Tina Smith, Univ. of Mass. extension floriculture specialist, said some growers confuse hunter flies with shore flies.
Adult shoreflies, which are smaller than hunter flies, have short robust bodies, short legs and short antennae. Hunter flies are darker in color and have 5 clear spots on their wings.
Adult hunter flies prey on other flying insects, including fungus gnats, shore flies, leafminer adults and, to a lesser extent, whiteflies. They catch their prey in flight.
Hunter fly larvae live in the soil and are predators of soil-dwelling organisms including fungus gnat and shore fly larvae. Larvae grow for about two weeks and then pupate in the soil for two weeks.