Armyworms are frustrating foes to the rancher, traveling in mass across fields and devouring all grass in their path. Natural predators normally control the armyworms. Predators include a fungus and a wasp that lays an egg on the worm. However, extremely dry weather slows the development of the fungus, which needs moist conditions to flourish.

Pastures damaged by armyworms will require intensive management to recover. "For established stands of fescue pasture, this will be a minor blip," says Rob Kallenbach of the University of Missouri-Columbia agronomy department. "But for newly seeded stands of forage, the armyworms may have been too much.

"The main thing is to give severely damaged pastures time to rest and recuperate. Cattle should be removed," says Mr. Kallenbach. "The established stands will have enough reserves stored in the root system to come back. They just need 30 to 60 days of rest. That is where the new stands will suffer. They won't have the carbohydrate reserves in their roots to put up new shoots."

To help recovery of pastures that have been chewed up by the army of armyworms, consider an application of nitrogen to grass pastures. "The added fertility should extend the grazing season," says Mr. Kallenbach.

Farmers whose fields were not hit by the worms should keep a lookout for new outbreaks, according to Wayne Bailey, MU extension entomologist. "There were an awful lot of moths flying. There may be a second generation." Check pastures regularly for armyworms. Very young worms are small green "loopers" that travel like an inchworm. Mature worms are up to 1.5 inches long.