Broadleaf weeds, such as dandelions, will remain untouched. Jim Scott, superintendent of Purdue's Birck Boilermaker Golf Complex, says armyworms attack the grass blade, not the crown where growth takes places. With adequate moisture, the blade will regrow in seven to 10 days, he says. Don't spray the entire lawn. Find where the larvae are feeding and spray 100 feet beyond the area.
Perimeter spraying keeps other larvae from moving in.
Even though homeowners should wait to spray, they can monitor field conditions around their property. Obermeyer says pastures and fields damaged by armyworms will be stripped of foliage with only the plant stem remaining. Obermeyer says the gypsy moth caterpillar is often confused with the armyworm. Unlike the armyworm's diet of grassy-type crops, the gypsy moth caterpillar feeds on trees. Obermeyer says he expects the armyworm problem to subside in a couple of weeks.