AbstractAdults of the predatory fly Coenosia attenuata Stein (Diptera: Muscidae) catch their prey while in flight. I investigated this activity over two seasons in a tomato greenhouse naturally infested with Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). The flight of C. attenuata individuals was affected by environmental factors and was increased in response to increases in temperature, the number of prey flights, and conspecific density. Predator and prey flights were distributed throughout the day, but there was a regular daily trend, each with two partially overlapping activity peaks. The possibility of predation was limited by differences in daily flight‐activity times. Predatory flights comprised a small percentage (ca. 6%) of the total flights, with a predation success rate of 61%. Overall, the predatory activity of C. attenuata depended on the selection of hunting sites with good visibility to ensure a clear view before take‐off and allow the capture of prey in flight. Similar numbers of overall flights were made by both sexes, but C. attenuata females performed more predation flights and territorial defense activities than males. The ecological role of C. attenuata and its limited adaptability to greenhouses is discussed in light of its possible use in biological control of whiteflies.