The western bean cutworm (Striacosta albicosta, Smith) is a native pest of dry beans and corn in western North America, and since 2000, has expanded its range eastward to include Michigan. It was discovered in the state in 2006, and has been reported as a pest of Michigan dry beans and corn since then. Michigan is the second largest producer of dry beans in the United States, and western bean cutworm was a new threat to this industry. Our overall objective was to study western bean cutworm biology and control to develop management recommendations for Michigan dry bean growers. Moth flight was monitored, and range expansion was tracked, through a pheromone trap network from 2006 - 2012. In central Michigan, pheromone traps near dry beans caught significantly more moths than traps near corn. Health of egg masses decreased due to possible predation, fungal pathogens, and proved parasitism. Western bean cutworm larvae have the potential survive on alternate host plants, many of which are produced in Michigan's diverse agriculture. Larvae are difficult to scout for in dry beans because they remain on the ground during the day. Prepupae are found overwintering as deep as 38 cm in the soil. Significant damage to dry bean quality and marketable yield was observed with 1 egg mass per 1.5 m of row or 2 larvae per 0.3 m of row. A spray application of λ-cyhalothrin 1 to 2 weeks after local peak flight offers the most effective control of western bean cutworm in Michigan dry beans.
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