Abstract
Preliminary tests showed that, though Nasonia vitripennis (Walk.) can be propagated on housefly (Musca domestica (L.)) pupae at any stage of development, females parasitizing pupae less than 48 hours old, at 21.5°C., lived longer than those parasitizing older pupae. In view of the fact that the females always feed on the pupae after ovipositing on them, it seemed possible that the greater longevity of females parasitizing and feeding on young pupae had resulted from more suitable food provided by these pupae. As plans had heen made to investigate experimentally the host-finding capacity of this parasite species, it was essential that any effect of host age on this capacity, or on biological attributes of the parasite that influenced it, be standardized. Tests were therefore made to determine the effects, if any, of a host's age on the longevity and fecundity of female N. vitripennis laying and feeding on it.