The genus Wormaldia McLachlan 1865 (Trichoptera: Philopotamidae: Philopotaminae) is one of eight Philopotamidae genera found in the New World. In the Nearctic Region five genera are reported: Chimarra, Dolophilodes, Fumonta, Sisko, and Wormaldia. This last genus is diverse and widely distributed from Canada to South America; for the Nearctic Region the following species are reported: W. anilla (Ross, 1941), Canada, USA; W. arizonensis (Ling, 1938), Mexico, USA; W. gabriella (Banks, 1930), Canada, USA; W. gesugta Schmid, 1968, USA; W. hamata Denning, 1951, USA; W. lacerna Denning, 1958, USA; W. laona Denning, 1989, USA; W. moesta (Banks, 1914), Canada, USA; W. mohri (Ross, 1948), USA; W. occidea (Ross, 1938), Canada, USA; W. oconee Morse, 1989, USA; W. pachita Denning, 1956, USA; W. planae Ross and King, 1956, USA, W. shawnee (Ross, 1938), USA; W. strota (Ross, 1938), USA; and W. thyria Denning, 1950, USA. Diagnoses, redescriptions, and illustrations of the forewing, the hind wing, and the male genitalia of the 16 species are provided. New state distribution records are given for W. anilla, W. gabriella, W. occidea, W. planae, and W. shawnee. Two undescribed Nearctic species are diagnosed, described, and illustrated: Wormaldia birneyi, new species, from USA (California) and W. clauseni, new species, from Canada (British Columbia). A key for identification of males of these 18 species of Wormaldia is provided, as well as maps of their Nearctic distributions.