Morphological characters to separate Psorophora horrida (Dyar and Knab) and Psorophora ferox (Von Humboldt) females are identified and defined. In addition to the 3 characters used to separate these 2 species in published keys, an additional 6 characters were found. Of the total of 9 characters identified, 6 are reliable at the 100% level, based on North Carolina specimens. These additional characters will assist greatly in identifying Ps, horrida specimens. Variation or hindtarsomere 4 of Ps. horrida, consisting of dark-scaled patterns, were also noted. Characters for separating Psorophora cyanescens (Coq.) and Psorophora mathesoni Belkin and Heinemann from Ps. ferox and Ps. horrida are discussed.