Posted by John Carr on 29-01-2018 23:33
#3
The keys I have are based on wings. In the key to
Neoempheria in
Insects of Connecticut (Shaw and Fisher 1952) it goes to
nepticula (Loew) or
impatiens Johannsen. In Johannsen (1910) it goes to
nepticula Loew. The two species are very similar. One key character is the position of the sc-r crossvein ("Sc2") relative to the base of Rs. Your fly has opposite character states on opposite wings.