Virus-like particles (VLPs) that are bound to the egg surface of a parasitic wasp Venturia canescens are void of nucleic acid and unable to infect host tissue but instead provide a passive protection against the host's immune recognition. To investigate evolutionary and functional properties of Venturia particles, we isolated cDNAs coding for a VLP-protein by screening an expression library of the wasp, using antibodies against purified VLPs. The corresponding coding DNA is present in the wasp genome as a single-copy gene.