I recently found this bean leaf beetle (Cerotoma trifurcata, Chrysomelidae) overwintering in a rotting log. It was a bit sluggish but seemed displeased with being handled. Although colors and patterns can vary within this species, one consistent characteristic is the black triangle on the front of the elytra (the hard wing covers).
These beetles feed primarily on the leaves of legumes, especially the soybeans (Glycine max, Fabaceae) that are abundantly grown here in southern Michigan. It’s one of the most damaging soybean pests in North America.