Serological tests were done to examine the relationships between twelve picorna-like viruses of insects. The results of the tests indicated that the majority of the viruses are unrelated. However, cricket paralysis virus, isolated from Australian wild field crickets, appeared to be identical to Drosophila C virus, independently isolated in France. Cricket paralysis virus was infective for adults of Drosophila melanogaster and its infectivity towards Galleria melonella was neutralised by Drosophila C virus antiserum. It is therefore concluded that cricket paralysis virus and Drosophila C virus are very closely related if not identical.