The Collaborative International Dictionary
buffalo gnat
black fly \black fly\, blackfly \blackfly\, (Zo["o]l.)
In the United States, a small, venomous, two-winged fly of the genus Simulium of several species, exceedingly abundant and troublesome in the northern forests; -- called also buffalo gnat. The larv[ae] are aquatic. It sucks the blood of birds as well as humans and other mammals.
A black plant louse, as the bean aphis ( Aphis fab[ae]), which infests e. g. beans and sugar beets; -- called also bean aphid.