Host finding abilities were investigated in the braconid Coeloides bostrichorum and the pteromalid Rhopalicus tutela, two ectoparasitoid wasps attacking the late instar of the bark beetle Ips typographus. Under laboratory conditions, important differences in the host-searching behaviour of these species were found, R. tutela being highly mobile as compared to C. bostrichorum. In the presence of C. bostrichorum, R. tutela behaved as a cleptoparasitoid, displacing the females from their oviposition sites and stealing the hosts previously located by the braconid. This behaviour facilitated host finding in R. tutela and could partly explain the relative success of the polyphagous R. tutela when occurring with the more specialised C. bostrichorum. Nutrition; Feeding behaviour; Foraging; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Ecological niche; Competition Ips typographus (Curculionidae); Hymenopteran parasites; Coeloides bostrichorum & Rhopalicus tutela; Interparasite kleptoparasitism effects on host finding ability of competing parasites; Plant hosts Coeloides bostrichorum (Braconidae); Coleopteran hosts; Kleptoparasitism by hymenopteran competitor effects on competitor host finding ability; Resource partitioning; Interspecific competition Rhopalicus tutela (Pteromalidae); Food robbing; Coleopteran hosts; Ips typographus; Parasite kleptoparasitism of hymenopteran competitor effects on host finding ability; Resource partitioning; Interspecific competition none