Getting a few calls about these large caterpillars in seedling soybeans. These caterpillars are the larva of the lined sphinx moth. They will reach a size of around 3-inches long when fully grown. As these caterpillars reach maturity they can consume a large amount of plant material, luckily they do not feed on soybeans. Instead, we sometimes find them in large numbers in fields feeding on weeds. Cutleaf evening primrose seems to the predominant weed we see them feeding on. Often, they will migrate from fields in large numbers when they have defoliated their host plants. Since these insects do not feed on the soybeans and do feed on the weeds in the field, I suppose we should consider them beneficial. There is no need to get excited and treat for these insects in soybeans.