The emphasis in arthropod biological control has traditionally been to make use of natural enemy consumption of prey in order to manage pest abundance. This focus has yielded many effective biological control programs but it has largely ignored an important aspect of the dynamics that unfold among insect pests and their arthropod natural enemies. Arthropods respond to risks from pre dation and parasitism changing activity level and/or habitat use (Lima, 1998). These chan collectively classified as non-con- sumptive effect of natural enemies, can substantially influence the abundance of herbivorous insects and the plant damage that these insects cause (Nelson et al., 2004; Nelson and Rosenheim 2006: Thaler and Griffin. 2008). It is now apparent that non-con- sumptive effects by predators are important in many food webs and could even exceed the magnitude of the consumptive effects in regulating prey populations (Relyea. 2001; Werner and Peacor, 2003: Lutt beg and Kerby, 2005: Preisser et al., 2005: Thaler and