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Adults are dull brown or grayish, relatively large, up to 1-1/2
inches (3.8 cm) long, night-active moths. Larvae are caterpillars
that are up to 2 inches (5 cm) long at maturity and often curl up
and lie still when disturbed. The large size and behavior of larvae distinguish them
from lawn moth caterpillars.
All turfgrass species
Cutworm and armyworm larvae chew and cut leaves around the crown.
Damage begins in small, irregular spots and spreads to patches extending
many feet in width. Armyworms, especially, prefer moist areas.
Cutworms and armyworms are active from early spring through the
fall. Look for fat, dull gray, green, or brownish larvae up to 2
inches (5 cm) long with a drench test.
Inspect outdoor lights around dawn for 1-1/4 inch (3.2 cm) brownish
to gray moths.
Reduce thatch and eliminate
soggy areas. Larvae have some natural enemies, such as braconid
wasps and tachinid flies.
If more than 5 larvae per square yard are present, you may need to
treat. Beneficial nematodes or an application
of Bacillus thuringiensis (Bt) may be effective against young
caterpillars. Other safe products are available.
For more information on lawn insects, refer to:
Pest Notes: Lawn Insects