Armyworms and fall armyworms have been active this year, as usual, but not nearly as active or damaging 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. When grass is unavailable, however, they will readily consume broadleaf plants such as soybeans.

By now, armyworm larvae have matured and pupated, after which they become moths. Reminder: Fall armyworms don’t overwinter in Kansas. The moths 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 that fit that description. Thus, monitoring wheat fields for small larvae should start after germination. Armyworm feeding may continue until the first hard freeze, meaning temperatures in the mid-20s 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 entomology specialist.

Stacy Campbell is an agriculture and natural resources agent for the Cottonwood Extension District. Email him at scampbel@ksu.edu or call the Hays office at 785-628-9430.