In this article, we explore the politics of expertise in an ongoing controversy in the United States over the role of certain insecticides in colony collapse disorder - a phenomenon involving mass die-offs of honey bees. Numerous long-time commercial beekeepers contend that newer systemic agricultural insecticides are a crucial part of the cocktail of factors responsible for colony collapse disorder. Many scientists actively researching colony collapse disorder reject the beekeepers' claims, citing the lack of conclusive evidence from field experiments by academic and industry toxicologists. US Environmental Protection Agency regulators, in turn, privilege the latters' approach to the issue, and use the lack of conclusive evidence of systemic insecticides' role in colony collapse disorder to justify permitting these chemicals to remain on the market. Drawing on semistructured interviews with key players in the controversy, as well as published documents and ethnographic data, we show how a set of research norms and practices from agricultural entomology came to dominate the investigation of the links between pesticides and honey bee health, and how the epistemological dominance of these norms and practices served to marginalize the knowledge claims and policy positions of commercial beekeepers in the colony collapse disorder controversy. We conclude with a discussion of how the colony collapse disorder case can help us think about the nature and politics of expertise. © The Author(s) 2012.