The bean leaf beetle, Cerotoma trifurcata (Forster), is an increasingly common early-season pest of soybeans, Glycine max (L.) Merrill, and snap beans, Phaseolus vulgaris L., in the upper midwestern U.S. In Minnesota, adults tend to emerge in late May from their overwintering sites. The adults readily transfer bean pod mottle virus to soybeans but most snap bean cultivars are resistant to this virus. However, the beetles can cause extensive defoliation of young legume seedlings. Although considerable research has been published regarding the defoliation potential of C. trifurcata in soybeans, thresholds for defoliation have not been established for snap beans. We are developing enumerative sampling plans to estimate the beetle’s population densities and sequential sampling plans to provide the basis for pest management decisions. We took 60 individual plant samples from experimental plots and commercial fields in 2003 and 2004 at the Rosemount Research Station in Minnesota. Resampling software was used to validate the enumerative plan, based on Taylor’s power law parameters. In addition, we developed action thresholds for C. trifurcata in snap beans (a 60-day crop) focusing on the early growth stages using cage and simulated defoliation studies.