Fall Armyworms in Turf

Wednesday September 08, 2010 - Fall Armyworms in Turf

In late summer, almost every year, caterpillars invade turf grass throughout the state. The damage to established turf is mostly aesthetic, but newly sodded or sprigged areas can be more severely damaged. While there are several caterpillars that can damage turf grass, in late summer most of the problems are from fall armyworms. Their favorite turf to feed upon is Bermuda grass.

Adult armyworm moths are active at night. Damage from small larvae may at first look like skeletonizing, but as the worms grow, the entire lead is consumed. Armyworms are most active early and late in the day, spending the hotter hours down hear the soil in the shade. Larvae feed for 2-3 weeks before pupating in the soil. Moths emerge 10-14 days later. The entire life cycle from egg to moth takes about 28 days in the warm weather of August and September. If there is any doubt about whether worms are present, pouring soapy water on the grass (1/2 oz. dishwashing soap/gallon of water) will bring them up very quickly.

Control of Armyworms and other turf caterpillars is relatively simple once the problem is identified. The old standby carbonyl (Sevin, etc.) still works well, as do all the pyrethriods (Pyrethriods are those active ingredients that end in 'thrin').

It is not necessary to water after the application, but please do not cut your grass for 1-3 days after the service is completed.

Remember, Armyworms will not kill an established lawn, but those with newly sodded turf should be more cautious when you see them active in the turf.