Black fly Meaning, Definition & Usage

  1. noun small blackish stout-bodied biting fly having aquatic larvae; sucks the blood of birds as well as humans and other mammals
    blackfly; buffalo gnat.

WordNet

Definitions
  1. . (Zoöl.) (a) 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. The larvæ are aquatic. (b) A black plant louse, as the bean aphis (A. fabæ).

Webster 1913