Technical Abstract: Little is known regarding differential susceptibility of lady beetles species to entomopathogens, and how these entomopathogens affect lady beetle populations in the field. Previously, we found that a native North American lady beetle species, Olla v-nigrum, was commonly infected by Beauveria bassiana in the field. In laboratory assays, O. v-nigrum was susceptible to B. bassiana recovered from naturally-infected O. v-nigrum whereas, an exotic lady beetle, Harmonia axyridis was not. We hypothesize that a relative lack of susceptibility by H. axyridis to entomopathogens has facilitated the establishment of this exotic species across North America. Here we have tested the susceptibility of four North American lady beetle species (Coleomegilla maculata, Hippodamia convergens, Cycloneda munda and O. v-nigrum), to the commercially-available GHA strain of B. bassiana and B. bassiana collected from naturally-infected O. v-nigrum. Our results showed differential susceptibility of lady beetle species to B. bassiana. Mortality of C. munda and O. v-nigrum treated with B. bassiana isolated from O. v-nigrum was significantly higher than mortality of those beetles treated with the GHA strain of B. bassiana and control mortality. In contrast, no difference in mortality of C. maculata or H. convergens was detected between treatments.