I was recently asked about an alien-looking caterpillar from central Nebraska. I occasionally see silver-spotted caterpillars in Iowa and wondered if you were seeing any in soybean?
The caterpillars are definitely a unique species because of the body coloration! The bodies are yellow-green in color and the head is brownish red. The caterpillars can make webbed nests similar to thistle caterpillar. They like to feed on locust trees, legumes, and wisteria.
The adults have distinctive silvery markings on the wing edges. The wings are chocolately brown with banding, and about 2.5 inches wide. Likely there is one generation in Iowa/Nebraska. The adults like to feed on milkweed, red clover, and thistles.