The emerald ash borer (EAB), an exotic wood-boring beetle from Asia, was identified in 2002 as the cause of ash (Fraxinus spp.) mortality throughout southeastern Michigan and southwestern Ontario. Due to the transport of infested ash nursery stock, logs, and firewood, EAB infestations are now known in Ohio, Indiana, Maryland, and Virginia. Successful control of EAB in North America can only be achieved by aggressive quarantine enforcement and reductions in field populations using a variety of management tools. We are evaluating the efficacy of the entomopathogenic fungus Beauveria bassiana GHA, formulated as the bioinsecticide BotaniGard ES, against EAB larvae and adults after application to trunks of infested ash trees. We will report on spring pre-emergent trunk sprays in greenhouse and field trials where up to 76% of adults died from B. bassiana infection. Applications of BotaniGard to infested tree trunks in the fall resulted in some larval infections. The potential use of BotaniGard to protect uninfested ash trees from EAB will also be discussed.