The ability of 3 populations of X. diversicaudatum to transmit arabis mosaic virus (AMV) and 3 strains of strawberry latent ringspot virus (SLRV) was tested in laboratory experiments. X. diversicaudatum from Scotland readily transmitted the type strains of AMV and SLRV from Britain but did not transmit 2 strains of SLRV from Italy. A population of X. diversicaudatum from Italy transmitted all 4 viruses, but only with a small frequency. X. diversicaudatum from France did not transmit a strain of SLRV from Italy, transmitted the SLRV from Britain only infrequently, and transmitted AMV with a frequency intermediate between that of the Scottish and Italian populations. Anatomical and morphological studies showed the 3 populations were all X. diversicaudatum but that the Italian and French populations were significantly smaller than the Scottish. Electron microscope examination of thin sections through the oesophagus and odontophore indicated that infrequent or non-transmission of virus was related to lack of retention of virus within the nematodes.