If you read the bean leaf beetle prediction in the May 1 ICM newsletter, you'll know that winter mortality of this soybean pest is expected to be at a 12-year low. The result will be that we should have more bean leaf beetles this spring than during an average year. In fact, our predictions, based on summer population increases during the last several years coupled with the mild winter, are for the populations to be very large. Bean leaf beetles look much like black-spotted yellow, brown, or brick red lady beetles. Unlike lady beetles, bean leaf beetles have a prominent black triangle at the front of the wing covers that points backward and most, but not all, have a series of rectangular spots on the wing covers.
Adults occur in two color phases, red and yellow.
Bean leaf beetles have the noticeable habit of abruptly dropping to the ground and scurrying into cracks and crevices when disturbed. Crop scouts need to approach infested plants carefully and watch for this behavior to estimate population size effectively. The yellow phase of the bean leaf beetle is the most common color variety. Some bean leaf beetles are red instead of yellow. Bean leaf beetles are commonly found on alfalfa after emerging from their winter habitat.