Psocoptera are a paraphyletic group of insects that are commonly known as booklice, barklice or barkflies. The name Psocoptera has been replaced with Psocodea in recent literature, with the inclusion of the former order Phthiraptera into Psocodea.

Troctomorpha is one of the three major suborders of Psocodea (barklice, booklice, and parasitic lice), alongside Psocomorpha and Trogiomorpha. There are more than 30 families and 5,800 described species in Troctomorpha. The order includes parasitic lice, which are most closely related to the booklice family Liposcelididae.