–by Dr. Jeff Whitworth — Field Crops
Green cloverworms are quite common right now in most alfalfa and soybean fields throughout north central Kansas. They are in various stages of development (see fig. 1), i.e. sizes are variable, but most will be pupating within a week or two. The adult moths will then emerge, mate, and start depositing eggs, probably mostly in soybean fields. This next generation of green cloverworm larvae then maybe more significant as they are voracious leaf feeders and can quickly cause noticeable defoliation in soybeans. Populations of green cloverworms have occurred in significant densities periodically in past years as to cause considerable concern. Defoliation of 50-60% during the vegetative stage may justify an insecticide application. However, there is often an entomopathogenic fungus that attacks green cloverworm larvae when the larvae reach significant densities. This fungus can really decimate these larvae and thus help control their populations.
Figure 1. Green Cloverworm (pic by Cody Wyckoff)