How to Get Rid of Army Worms? | Stop Lawn Damage Now

Army worms are controlled by scouting, hand-picking small infestations, and applying a labeled insecticide when counts exceed thresholds.

The key to stopping them is catching the infestation early and treating at the right time of day. Here’s the straight path to getting rid of army worms and protecting your lawn.

Confirm Army Worms Are Actually Present

Before reaching for a spray, confirm you’re dealing with army worms and not another lawn pest. Army worms are caterpillars that feed at night and hide during the day. Look for them in the early morning, especially around the edges of brown or damaged patches. You’ll also see their droppings, which look like small green or brown pellets, and you may spot moths flying low over the grass at dusk.

To test for larvae, mix about one teaspoon of dish soap into a gallon of water and pour it over a one-square-foot section of damaged turf. The soap irritates the caterpillars, forcing them to the surface within a few minutes. Count what appears.

Use the Right Treatment for the Infestation Size

For a small number of caterpillars, hand-picking into soapy water is effective. For larger outbreaks, targeted insecticides are the most reliable control. The table below outlines the standard options.

Spray at the Right Time, the Right Way

Spraying at the right time of day matters as much as the product you choose. Army worms feed mostly at night, dawn, or dusk, so apply contact insecticides in the late afternoon or early evening when larvae are active and exposed. For products like Bt, wait until most eggs have hatched — it only works on young feeding larvae, not eggs.

Apply by these rules:

• Treat the whole affected area and the advancing edge of the infestation, not just the visible brown patches. Larvae often move in from adjacent green turf.
• Do not water the lawn and avoid applying if rain is expected within 24 hours of a contact insecticide application — moisture washes the product off before it works.
• Mow late in the day before treatment only if the label and turf conditions allow, then apply the insecticide to expose larvae to the product.

Scout after treatment to confirm the larvae are gone. If your lawn matches these numbers, treatment is justified. For choices on lawn-approved sprays, see our roundup of the best army worm sprays tested for US lawns.

Clean Up to Prevent a Second Round

After the current infestation is controlled, take steps to keep army worms from coming back. Larvae feed on grassy weeds and excess growth, so removing weeds and keeping thatch under control removes their food source. Avoid over-fertilizing and over-irrigating, which creates lush growth that attracts moths looking to lay eggs. In garden beds, fall tillage can reduce overwintering pupae in the soil.

Always follow the product label exactly — it controls the legal use, dose, and whether a product is approved for turf, gardens, or crops. Wear gloves, long sleeves, pants, goggles, and closed-toe shoes when handling any pesticide. Note that broad chemical spraying can also kill beneficial insects, so use targeted treatments only when thresholds are met.