How to Get Rid of Army Worms

Getting Rid of Army Worms

In Florida, armyworm trouble usually builds in late summer and fall, not spring. Walk the lawn weekly during those months, starting with sunny areas. Small caterpillars are easier to control, so catching them early limits damage.

Stopping Armyworm Damage and Helping the Lawn Recover

Before doing anything, make sure live caterpillars are still in the grass. Brown patches often become obvious only after the caterpillars have finished feeding and moved into the soil to pupate, and treating at that point does nothing for the lawn. Part the grass where brown turf meets green turf, since that edge is where active feeders usually are. The armyworm infestation page explains how to check.

• Water to support regrowth. Armyworms chew the leaf blades but usually leave runners and roots alone, so an established St. Augustine or bermudagrass lawn often greens back up with regular watering, within your local watering rules.
• Mow at the recommended height for your grass type and avoid scalping areas that are already thin.
• Cut back on night lighting near the lawn. The adult moths fly at night and gather at lights.

Common mistakes: pulling up and re-sodding before giving the grass a few weeks to recover, treating in the heat of the day when caterpillars are hidden down in the thatch, and assuming every brown patch is armyworms when chinch bugs, drought stress or fungal disease can look similar.

A professional visit starts with an inspection to confirm which pest, if any, is causing the damage. Treatment is then aimed at the active areas and timed to when the caterpillars feed, which is mostly at night and early in the morning. In warm weather a new generation can follow in about a month, so a follow-up check is part of the plan.