buffalo gnat vs black fly

buffalo gnat and black fly both are nouns.

Word	Noun	Adjective	Verb	Adverb
buffalo gnat	Yes	No	No	No
black fly	Yes	No	No	No

As nouns, buffalo gnat and black fly are synonyms defined as:

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

Other synonyms of buffalo gnat include blackfly.

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