Three virus-like particles have been isolated from diseased larvae of Antheraea eucalypti. Serological tests established that one of them was indistinguishable from cricket paralysis virus (CrPV). CrPV isolated from crickets and from Antheraea were cross-infectious, and crickets could acquire lethal doses of the virus by feeding on infected Antheraea larvae. In addition to two species of Teleogryllus, three other species of Orthoptera and nine out of ten species of Lepidoptera tested were susceptible to the virus. It is suggested that CrPV may have originated amongst the Lepidoptera and has been acquired by the field cricket by infectious passage along a food chain.