Among insect pathogens, Bacillus thuringiensis subsp. kurstaki (Btk) and Plodia interpunctella granulovirus have been reached commercialization for control of stored product Lepidoptera, but have limited use. Coleoptera lack microbial insecticide products but have many natural microbial control agents, especially among Protozoa and Microspora. Deuteromycete entomopathogenic fungi infect insects across orders, including beneficial Hymenoptera, with varying efficacy. Beauveria bassiana is emerging as the most promising mycoinsecticide for stored-product insects, along with Metarhizium anisopliae. Efficacy can be increased with synergies, such as with desiccant dusts. Surprisingly, environmental desiccation can also increase efficacy in some cases. Nonspecific fungi are not compatible with beneficial wasps. Protozoa in the genus Mattesia also infect both pest insects and parasitoid wasps, but infected wasps survive for several weeks and can serve as dispersal agents. Thus, while in vitro production of Mattesia spp. has not been achieved, they are not viable commercial pest control agents, they may be valuable natural controls worthy of conservation and introductions.