Definitions for "blackfly"
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 larvæ are aquatic. It sucks the blood of birds as well as humans and other mammals.
A small gnat like swarming, annoying, biting insect that comes out usually around Memorial day thru the 4th of July.
an aquatic macroinvertebrate of the order Diptera, a true fly. Dumbbell-shaped, soft larvae attach themselves to the substrate and prefer soft sediment; they are pollution tolerant.
Keywords:  beets, aphid, infests, aphis, louse
A black plant louse, as the bean aphis (Aphis fabæ), which infests e. g. beans and sugar beets; -- called also bean aphid.
blackish aphid that infests e.g. beans and sugar beets
Blackfly was a Canadian sitcom which ran on the Global Television Network for two seasons (2001-2002).