Parasitic wasps that lay their eggs in or on the bodies of other insects such as aphids or caterpillars and use these insects as a host for development of their offspring, are well known to use plant odours in location of their hosts. When these aphids or caterpillars feed from the plant, they induce changes in plant odours that the parasitic wasps use as a reliable cue of where their hosts are located. However, when the plant or plant stand is under attack by multiple herbivores and these interactions take place in complex habitats, host location by parasitic wasps is less straight forward. I study how habitat complexity, such as presence of multiple herbivores, affects efficiency of host location and which strategies parasitic wasps evolved to cope with complex environments.