Key to Nealyda Dietz in the United States and Caribbean based on external features

1. Forewing proximal half pale brown to dark ocherous brown.................................... 2

— Forewing proximal half gray, with or without brown irroration.................................. 5

2(1). Forewing divided by a single medial fascia................................................... 3

— Forewing not divided by a single medial fascia or multiple fasciae present......................... 7

3(2). Forewing proximal half ocherous brown to dark brown; apex of wing deeply infuscated; midwestern and southwestern United States .............................................. N. bifidella Dietz

— Forewing proximal half tan to pale yellowish brown; apex of wing slightly infuscated with patchy black scales; Florida, United States ............................................................ 4

4(3). Forewing distal half gray, distinctly contrasted with proximal half along fascia; hindwing light gray....................................................................... N. kinzelella Busck

— Forewing distal half tan brown, concolorous with proximal half; hindwing light brown............................................................................ N. pisoniae Busck (in part)

5(1). Forewing dark gray, brown irroration present; hindwing deeply infuscated at apex.................................................................................... N. phytolaccae Clarke

— Forewing pale gray, sometimes slightly metallic, without brown irroration; hindwing slightly infuscated at apex.............................................................................. 6

6(5). Bahamas .......................................................... N. pisoniae Busck (in part)

— Big Pine Key, Florida .................................... N. grandipinella Bennett and Hayden

7(2). Proximal half of forewing brown, distal half gray; margins of colors distinct but without medial fascia; hindwing pale gray; West Indies N. bicolor (Walsingham)

— Forewing pale brown, divided into thirds by two thick dark ocherous brown fasciae; hindwing dark brownish gray; Cuba N. neopisoniae Clarke