Armyworm Control: How To Get Rid of Army Worms

Armyworms (also known as fall armyworms) are the larvae of moths and are common turf pests in yards and landscapes. As larvae, armyworms feast on a variety of crops and turfgrasses. When multiplying in large numbers, they often move together toward new areas to consume food, which resembles a marching army—hence the origin of their name.

Armyworms are mainly found in the southern part of the United States. They like to reside on turf, such as Bermudagrass, and infest lawns, causing moderate to severe damage. Signs of trouble from armyworms may appear in brown grass, which novice lawn owners mistake for the grass not getting enough sunlight or water. What is happening is that armyworms are chewing blades of grass, zapping the plant of its nutrition.

If you are dealing with armyworms on your lawn or garden, our professional DIY treatment guide can help. Compiled by our staff of lawn care experts, this guide can help you eliminate armyworms step-by-step quickly and affordably. Follow the directions provided and use our recommended products, and we guarantee success in killing the armyworm population on your lawn.

Identification

Before you can carry out a pesticide application, you must ensure that you face an armyworm infestation through identification. Careless identification can lead to using the wrong insecticide products, which can waste time and money. Below are common characteristics of the armyworm that can be easily identified. 

• Armyworm caterpillars can be light green or tan in their early growth stage and dark green or brown in later stages. Fully grown larvae range between 1 and 1.5 inches long and are hairless. Their distinguishing traits are a series of green, yellow, or brown stripes down the length of their bodies.
• Armyworms have brown to light brown head capsules with a Y shape. They can often be seen moving in large groups. Armyworm activity is usually highest from summer to early fall.

Use the image and description above to help you identify armyworms on your lawn. If you are having trouble confirming that the pest on your property is an armyworm, contact us with a quality close-up photo. We will be happy to respond with the pest identified and offer suggestions and product recommendations to eliminate it.

Inspection

Once you have properly identified the armyworm, you can move on to inspection to observe where the most activity is occurring and where they are concentrated so you can focus your treatment on these hotspots.

When to Inspect

Observe your lawn and garden for signs of armyworms to find where the most activity occurs and where their eggs and larvae are concentrated. Scan your yard, specifically suspicious areas where you notice damage via discolorations or dead grass.

What to look for

It would be best to look for armyworm activity on your turf or damage left by armyworms in discolored grass. Determine whether you have a small or large infestation. It's best to treat early if you find an infestation, as armyworms inflict the most damage during dry and hot summer weather.

Armyworms are active in the early morning, late evening, and nighttime. During the day, They hide under leaf litter and thatch. To flush them out of hiding, use a solution containing 1 gallon of water and 1 tablespoon of dishwashing liquid and pour it over suspected patches. If they are present, they will float to the surface within minutes.

Treatment

Our top pesticide suggestion for armyworm control is a combination of Valar Plus Bifenthrin Granules and Supreme IT. These products are labeled to treat armyworms and deliver a powerful 1 to 2 punch, providing exceptional surface and subsurface control with a long residual, effectively eliminating the entire infestation.

Before conducting chemical applications, you should wear protective equipment when handling pesticides for any chance of skin or facial contact, which can be irritating or uncomfortable.

For insecticides to be effective, it is best to spray your selected product material early in the morning before 10 am, as armyworms mainly feed at night.

Step 1: Apply Valar Plus Bifenthrin Granules to the Lawn

Valar Plus Bifenthrin Granules is a granular insecticide that is labeled to control many turf pests, including Armyworms.

Start by calculating the square feet of your lawn or treatment area. Measure your lawn's length and width in feet and multiply them together (length x width = square footage).

To treat armyworms in your lawn, apply Valar Plus Bifenthrin Granules at a rate of 1.15 pounds per 1,000 square feet.

We recommend using a push broadcast spreader, similar to fertilizer, to apply the granules. You can also use a hand spreader for smaller patches of lawn.

Load your spreader with the proper amount of Valar Plus Bifenthrin Granules based on your square footage. Broadcast half the granules in parallel lines once across the area and then the other half at a perpendicular angle (like a grid pattern) so that the granules are evenly distributed over your entire lawn.

Once Valar Plus Bifenthrin Granules has been applied, it will need to be watered in to be activated. This will be done with Supreme IT in the next step.

Step 2: Mix and Apply Supreme IT to the Lawn

Supreme IT is a broad-spectrum liquid insecticide labeled for killing armyworms. It activates the Valar Plus Bifenthrin Granules and kills armyworms exposed to it, with a long residual effect that continues to kill for up to 90 days after application.

To apply Supreme IT, simply mix it with water in a handheld pump or hose-end sprayer.

Apply Supreme IT at a rate of 0.18 to 0.25 fl. oz. per gallon of water to cover 1,000 sq. ft.

You may have to apply a higher rate of 1 oz. per gallon if you have grass taller than one inch or if there is a severe infestation.

We recommend using a 20-gallon hose-end sprayer to more easily apply a broad treatment throughout the entire lawn. Make sure the sprayer's control valve and water pump are off, and then attach the hose-end sprayer nozzle to the hose. Remove the reservoir from the nozzle and then add the proper amount of Supreme IT and water.

When adding the product to the reservoir, plan to use 2 gallons of water per 1,000 sq. ft. Reattach the reservoir to the nozzle securely and then begin spraying by pushing forward on the control valve after turning the water onto the hose.

Broadcast the Supreme IT evenly over your yard and garden instead of spot-treating. Use a fan spray setting to get nice uniform coverage. Keep track of the amount of product in the reservoir. When it empties, no further product will be applied.

Apply Supreme IT in the late afternoon for best control, as armyworms are most active. Reapplications may be necessary until you see no further damage to your garden or the presence of armyworms has been wiped out. Make sure to postpone watering or mowing your lawn for 24 hours after application to obtain the best possible results.

Prevention

After eliminating the armyworm infestation, you will need to work to prevent the infestation from returning. The following preventative measures will ensure that armyworms will not return to your yard. 

• Monitor your garden regularly for any signs of damaged turf or leaves. Rake your lawn regularly to remove thatch and pick up yard debris, removing Armyworm hiding areas.
• Maintain a routine lawn care schedule that includes proper watering (1 to 1.5 inches a week) and mowing at a taller height (about 3 to 4 inches) to promote root growth.
• It would be best to fertilize your grass to ensure it gets the proper nitrogen to stay healthy and combat pest symptoms.
• Valar Plus Bifenthrin Granules and Supreme IT can also be a preventative application to keep armyworms away from your property. Apply quarterly for year-long control.

Key Takeaways

What are Armyworms?

• Armyworms are moth larvae known to feed on leaves and plants and colonize lawn turfgrass.

How To Kill Armyworms

• Valar Plus Bifenthrin Granules and Supreme IT are the best chemical treatments for armyworms. To achieve control, fully broadcast both products on your lawn and garden.

Preventing Armyworm Reinfestation

• Prevent armyworms from returning by combining cultural practices and preventative treatments of Valar Plus Bifenthrin Granules and Supreme IT.