We studied factors affecting the patch-leaving decision of the parasitic wasp Diadegma semiclausum, a parasitoid of diamondback moth (Plutella xylostella) larvae. Experiments were performed in a wind tunnel. We focused on two factors: (1) volatiles from host-food plants (infested or uninfested by hosts) upwind of the patch, and (2) the condition of the currently inhabited patch (the leaf). Irrespective of the upwind odor source, the wasp stayed longer on the infested patch than on the intact patch. The presence or absence of host larvae in the infested patch did not affect the time spent in the patch. Further, we found that the wasp used plural cues in the currently inhabited patch in their patch-leaving decision. Factors affecting the patch-leaving decision of the parasitic wasp were discussed in tritrophic contexts. Sensory reception; Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts Plutella xylostella (Plutellidae); Food plants; Brassica oleracea; Hymenopteran parasites; Diadegma semiclausum; Food plant volatiles evaluated as patch leaving cue for parasite Diadegma semiclausum (Ichneumonidae); Chemoreception; Lepidopteran host food plant volatiles; Lepidopteran hosts; Plutella xylostella; Host seeking & patch leaving decision cues none