none Drosophila melanogaster; AGE-; Pupae, influence on hymenopteran parasite hostfeeding preference; HYMENOPTERAN-PARASITES; Pachycrepoideus vindemiae; Hostfeeding, cost benefit analysis & preference between host species Asobara tabida; AGE-; Pupae, influence on Pachycrepoideus hostfeeding preference; HYMENOPTERAN-PARASITES; Pachycrepoideus vindemiae; Hostfeeding, cost benefit analysis & preference between host species Pachycrepoideus vindemiae; SIZE-; FECUNDITY-; Concurrent hostfeeding relationship, dipteran & hymenopteran hosts; DIPTERAN-HOSTS; Drosophila melanogaster; HYMENOPTERAN-HOSTS; Asobara tabida; Hostfeeding, cost benefit analysis & preference between host species; MORTALITY-; Offspring, relations with concurrent hostfeeding by female, insect hosts Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) is a facultative hyperparasitoid of Drosophila parasitoids in Europe. Female P. vindemiae host-feed from the same hosts into which they lay eggs and this enables them to mature additional eggs. P. vindemiae females were allowed to host-feed from puparia containing Drosophila melanogaster Meigen (Diptera: Drosophilidae) pupae or pupae of Asobara tabida Nees (Hymenoptera: Braconidae). Wasps which had host-fed carried significantly more eggs; the species of host which was fed from had no significant effect on the number of mature eggs in the ovaries. Host-feeding caused no significant reduction in the size of the emerging offspring. P. vindemiae were allowed to forage over patches containing different frequencies of the two host species. No significant oviposition preference was found but there were marked host-feeding preferences which were affected by the age of the host pupae. It is suggested that these preferences were due to the physical nature of the hosts which were fed from.