What Are Armyworms?

The Damage Armyworms Can Cause

The destruction caused by armyworms can be severe, especially when infestations go unnoticed. These pests feed on the leaves and stems of plants, stripping away vegetation and leaving behind bare patches. In lawns, armyworms chew grass blades down to the crown, giving it a scalped appearance. If damage is extensive, the grass will need reseeding and other intervention.

Crops like corn, rice, and soybeans are also at risk. Armyworms can consume entire fields if left unchecked. Their rapid reproduction and group-feeding behavior make them particularly challenging to control. Damage tends to spike during warmer month because hot weather accelerates their lifecycle.

To catch an infestation early, look out for these indicators:

• Sudden dead or brown patches in your lawn
• Visible caterpillars feeding on grass or plants
• Clusters of white eggs on blades of grass or leaves
• Increased bird activity (birds may flock to feed on the caterpillars)
• A “cut” appearance in plants where armyworms have chewed through stems and leaf blades

FAQ

How do I get rid of armyworms?

Effective control involves a combination of methods:

• Natural enemies of armyworms and beneficial insects can help reduce their numbers. Some natural enemies may be birds, skunks, ground beetles and other insects. 
• If you want to use insecticides, look on the insecticide label for active ingredients specifically targeting armyworms and apply them in the stage of development when the armyworm larva are small for the best results. 
• Regular mowing and removing debris like leaf litter from your lawn and soil surface can make it less inviting for female moths to lay eggs.

Are armyworms a threat year-round?

In most climates, no. Armyworms are most active during the warmer months and may not survive cold winters or cooler temperatures in many regions. However, in warmer climates or during unusually mild winters, they can persist year-round. Migratory moth flight can also bring new armyworm feeding infestations to previously unaffected areas with food sources, so be on the lookout every spring.

Can my lawn recover after an armyworm infestation?

It really depends on the severity of the damage. If the crowns of the grass are still intact, the lawn can regrow with proper care, including watering, fertilizing, and reseeding if necessary. For heavily damaged areas, you may need to lay new sod or overseed to restore the grass.