none Adult female Cotesia rubecula are attracted to and arrested by kairomones produced by the feeding activities of their obligatory host (Pieris-rapae). The ability to find a host depends almost exclusively on the wasps' behavioral responses to these chemical cues. Wasps do not readily leave plants that have host feeding damage. The time spent on a plant with feeding damage is further increased when a host is found because of the time spent recovering (grooming) from an attack on a host. This recovery time and the frequency of successful oviposition vary with host size. These results are discussed in relation to the parasite's foraging strategy.