Drosophila falleni is a species of fly found in northeastern North America. A mycophagous insect, it is known to feed on the fruit bodies (mushrooms) of several genera of fungi, including Agaricus, Amanita, Agrocybe, Boletus, Cortinarius, Pluteus Grifola, Polyporus, Hypholoma, Russula, Mycena, Stropharia, and Xerula. The fly can be infested by the parasitic nematode Howardula aoronymphium, which enters the fly larvae when it is feeding on mushrooms.