none This study describes the effects of host species (Anagasta kuehniella (Zeller) and Plodia interpunctella (Huebner) and size on the "functional" and "ovipositional" responses of the gregarious parasitoid Bracon hebetor Say, and its preferences between these host types. The "handling time" for A. kuehniella was greater than for P. interpunctella, and there was an active preference for attacking the latter; both results may be due to the defensive writhing of the former species. More eggs were laid on each parasitized A. kuehniella, which are larger and so can support more larvae (Taylor 1988), but there were no differences in the numbers of each species oviposited on.