Host selection behaviour of parasitoids has important fitness consequences, if hosts of different quality are available. Here the host selection behaviour, the ability to distinguish between hosts differing in their suitability, of the Drosophila parasitizing wasp Asobara tabida was studied. Females from five lines selected for higher survival in the encapsulating host species D. melanogaster (Kraaijeveld et al., 2001) were compared with females from control lines. Females from all five selected lines more readily accepted the encapsulating host species for oviposition when offered together with a nonencapsulating host species than females from the control lines. We found no evidence for pleiotropic effects and suggest that host selection behaviour evolved parallel to the ability to escape encapsulation in the hosts. Our results also suggest that given the appropriate selection pressures, host selection behaviour can quickly evolve in parasitoids, enabling them to adapt fast to changing circumstances. none