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Unfed nymphs ofthe Australian reptile tick species Aponomma hydrosauri and Amblyomma limbatum stayed in aggregated groups in one spot, despite the presence of host lizards as close as 50 cm. The two tick species apparently wait for hosts to come by, in contrast to other species which actively respond to nearby hosts. It may be that, because the bodies ofthe reptile hosts are so close to the ground, the ticks do not have to give up the benefits of remaining in sheltered microhabitats for efficient host finding.

Tests were conducted in Australia to determine the levels of reproductive isolation between geographically separated populations of reptile ticks. Mating behaviour was observed both on and off hosts in the laboratory when males were placed with females of their own or different populations. There was no evidence for reproductive isolation between South Australian populations of Aponomma hydrosauri (Denny) collected from the host lizard Trachydosaurus rugosus, despite one area of geographical isolation. Males of Amblyomma albolimbatum Neum. showed no discrimination between females from populations more than 2000 km apart. This contrasts with earlier reports of reproductive isolation between reptile tick species and contradicts hypotheses of rapid speciation in parasitic taxa.