Abstract
Parasites of Acrobasis spp. found in the Ottawa, Ont., area are separated by using characters of the parasite remains left in the host cases from which the parasites emerged. Characteristics of the cephalic structures, spiracles and skins of final-instar larvae of 28 species of parasites are described and illustrated in this paper; one species was described and illustrated in an earlier paper (Finlayson 1962); and one species is described from the literature. A record of all known species of Acrobasis parasitized by the species treated in this paper is tabulated.