Armyworms are causing serious damage to pastures and hayfields in several states.

The Environmental Protection Agency recently granted special registration to two insecticides – Pounce 3.2 EC and Confirm 2F – to combat the problem in Kentucky. Armyworms have been gorging themselves in the western part of that state for several weeks.

University of Kentucky extension entomologist Lee Townsend says armyworms do 90% of their feeding in the final stage of their life cycle, when they’re about 2" long. They can do a lot of damage in a short period, so unless pastures and fields are checked regularly, the problem often isn’t detected in time.

In addition to pastures and hayfields, the worms have been found in Kentucky wheat fields, and corn is another potential target. When the worms run out of leaf tissue in one field, they often move en masse to another.

They feed mostly at night, and during sunny days hide in soil cracks or under surface residue. If you don’t find worms, look for damage to leaf edges and droppings on the ground.

Kentucky extension entomologist Doug Johnson says the first armyworm generation is over in western Kentucky, but may still be active in the central and western parts of the state.

"It’s too early to tell how destructive the second generation will be," says Johnson.