The Kay County OSU Extension Office Gives Advice for Treating Army Worms

The Kay County OSU Extension Office in Newkirk has been getting quite a few calls about large groups of caterpillars eating yards. This is likely the Fall Armyworm and can be treated with some very selective insecticides.

When feeding, larvae strip foliage and then move to the next available food. High populations appear to march side by side to the new food. Thus, the name armyworms.

Besides warm-season turfgrasses, plants attacked by armyworms include grain and forage sorghum, corn, small grains, sweet potato, beans, turnip, clover, tobacco, spinach, cucumber, potatoes, tomatoes, cowpeas, cabbage, bluegrass, and others.

Damage consists of foliage consumption. The small larvae will chew the green layer from the leaves and leave a clearing or “windowpane” effect. The first three instars do very little feeding while the last two instars consume 85% of the total foliage consumed. Armyworms feed any time of the day or night, but are most active early in the morning or late in the evening.

According to the  Kay County OSU Extension office, the following insecticides are very selective and only kill true caterpillars and won’t even kill inchworms who aren’t true caterpillars, and should be available at most stores that sell home and garden products.