What do tiger-fly larvae (Diptera: Muscidae) eat?

Coenosia attenuata, usually known as tiger-fly, is a generalist predator of agricultural and forest pests in both larval and adult stages; it has potential to be an effective biocontrol agent in protected crops. To contribute for the knowledge of which prey this predator larvae potentially consumes, and of the occurrence and the conditions that promote cannibalism by tiger-fly larvae, intact alive specimens and portions of the earthworm Lumbricus terrestris were tested as prey and the cannibalism was evaluated in the presence or in absence of fungus gnat larvae. The tiger-fly larvae fed on the bisected earthworm portions but seem to have difficulty to penetrate in the cuticle of the alive and moving L. terrestris. However, the time to start feeding on the portions of L terrestris was shorter than on fungus gnats. Cannibalism by C. attenuato was not detected, but mortality occurred in several modalities. Nevertheless, escaping from the Petri dishes was the dominant behaviour of the larvae in the cannibalism evaluation assay.