The differentiation of the infective larvae of some common nematode parasites of cattle

Studies are reported on the differential diagnosis of the infective larvae of Strongyloides papillosus, Haemonchus contortus, Ostertagia ostertagi, Trichostrongylus axei, Cooperia oncophora, C. punctata, C. pectinata, Bunostornum phlebotomum, Nematodirus sp., and Oesophagostomum (Bosicola) radiatum, all of which occur in cattle in Queensland. These larvae can be readily identified by the length and shape of the tail, assisted by body length, body width, certain head and tail structures, and by the presence or absence of a sheath. A key for the identification of the larvae is given. Photographs of the larvae are also provided to assist identification.