Armyworms and fall armyworms have been active this year, as usual, but not nearly as active or impactful as in the past couple of years. Both species willingly feed on just about any green plant, but armyworms prefer grasses, such as corn, sorghum, wheat, brome, and turf. However, when grass is unavailable, they are more than willing to consume broadleaf plants such as soybeans.
By now armyworm larvae have matured, and have pupated, after which they mature into moths. Reminder - fall armyworms don’t overwinter in Kansas. The moth’s mate for a few days, then begin depositing eggs on or near green vegetation, and these eggs can hatch into new fall armyworm caterpillars. This time of year, in Kansas, alfalfa and wheat are the only two crops fitting that description, of having green vegetation. Thus, monitoring wheat fields for small larvae should start after germination. Armyworm feeding may continue until the first hard freeze, i.e., temperatures into the mid-20˚F for a couple of hours. Some years, armyworms have been active until mid to late November, depending on the weather.
Insecticide seed treatments do not control armyworms well enough to be recommended. Please refer to the 2026 K-State Wheat Insect Pest Management publication for wheat pest questions and recommendations.
Information provided by Jeff Whitworth, K-State Extension Entomologist Specialist.
Stacy Campbell is a Crop Production Extension agent in the Cottonwood District (which includes Barton and Ellis counties) for K-State Extension. You can contact him by e-mail at scampbel@ksu.edu or by calling 785-628-9430.