From Jennifer Grant, New York State IPM Program. See also IPM, Cornell on front lines of armyworm invasion (subscription required), Finger Lakes Times, 6/17/2012.

The scourge continues, with infestations that are unprecedented in New York. A western New York field crops consultant says he has never seen anything like it in his 45 years of experience. As discussed last week, when the caterpillars finish with a field they aggregate and move in massive numbers to the next available grass crops—often home lawns. If you catch the infestation early—as it begins invading your property, or when caterpillars are young if it started in the lawn, insecticide applications should be effective.

Take these steps: Monitor lawns, parks and golf courses. Watch for infestations on nearby crops and turfgrass, and their potential to move onto your property. Use soap flushes to detect caterpillars in turfgrass. You don’t need soap to detect the massive migrations, but if caterpillars are young or in low numbers, this detection and monitoring technique will be useful. If a lawn or other turfgrass area has been ravaged, provide frequent light irrigation to keep the crowns cool and moist. In most cases, the lawn should recover.

Images of some of the damage:

Armyworm damage to lawn.

Armyworm damage to lawn.

Armyworm damage to lawn.

Armyworm damage to lawn.

Armyworm damage to lawn.

Armyworm damage to lawn.