What Are Armyworms and How Do They Affect Your Lawn?

Lawn pests are often tiny creatures that can wreak havoc on the landscape, and among the most serious offenders are the armyworms. These small pests may go unnoticed until it’s too late, with their damage becoming evident—brown patches that spread quickly across your lawn. One day, your lawn may appear healthy and green, and the next, it’s covered with unsightly patches of chewed-up grass. 

Armyworms are aggressive little feeders that can destroy a yard if not promptly dealt with. If you see areas of your grass turning brown and find grass blades chewed or eaten away, it’s time to take immediate action. 

In this article, we’ll explore how to identify armyworms, their damage to lawns, and how to control and repair your turf. For help restoring your lawn, Bethel Farms offers high-quality grass for sale to repair any armyworm damage quickly.

Identifying Armyworms: What They Look Like at Every Stage

Armyworms are the larvae of moths and are known for their destructive feeding habits. Although initially small, their appetite and rapid development make them a serious threat to your lawn.

Early Stages: In their earliest stages, armyworm larvae are light green or tan. As they grow, they change color, eventually becoming darker shades of green or brown. This gradual transition makes it challenging to spot them early, but their presence becomes more evident as they grow.

Fully Formed Caterpillars: Once fully developed, armyworm caterpillars are about 1.5 to 2 inches long and are hairless. They are marked by a series of stripes running down their bodies and a distinctive Y-shaped mark on their heads. This makes them identifiable as armyworms, especially when feeding on your lawn.

Adult Moths: Adult armyworms are moths that are attracted to bright lights. In a single night, they can lay up to 1,000 eggs, typically near food sources like grass blades, fences, or house siding. Once hatched, the larvae spin silken threads to disperse and feed immediately.

Feeding and Damage: Armyworm larvae are surface feeders, beginning their work by chewing through the grass blades. Damage from armyworms intensifies after the 4th larval stage, with the larvae consuming a significant portion of the foliage. By the 6th stage, they burrow into the soil to pupate, emerging as adults 10 to 20 days later.

The entire life cycle of armyworms can be completed in about a month, with several generations potentially occurring in a single year. If left untreated, armyworm infestations can become a recurring problem throughout the growing season.

Signs of Armyworm Damage on Grass

Armyworms can leave significant damage on your lawn, and the signs are easy to identify once you know what to look for.

Early Damage

In the early stages of infestation, the damage caused by armyworms may look like drought or wilting symptoms. The grass will appear yellow or discolored, and patches may appear where the grass has been eaten away.

Later Damage

As the larvae progress through their stages, they consume more of the grass. This results in a scorched or scalped appearance, with most of the green foliage eaten away, leaving behind only the grass stems. The result is a lawn that appears patchy, with large sections of brown, dead turf.

Behavioral Signs

The word “army” in armyworms refers to their behavior: when armyworms are active, you may see them feeding or moving in large groups, especially in the early morning or late evening. They can cover large areas of your lawn in a short amount of time, leaving behind a trail of damage.

Feeding Habits

Armyworms consume grass rapidly, often moving from one area to another in search of food. They will continue to feed until the grass is nearly gone, causing widespread damage to lawns. Their feeding habits lead to large patches of brown, chewed-up grass, which can be devastating to your lawn's overall appearance.

While armyworms are primarily found in the Southern U.S., they can spread further north during the summer months, especially after tropical storms. These pests thrive on warm-season grasses like bermudagrass, but they can also attack cool-season turf during migration.

Effective Ways to Control Armyworms

Armyworms feed on the tips of grass blades, which makes them particularly vulnerable to insecticides when caught early. Treatment during the early stages of infestation can prevent them from doing significant damage to your lawn.

Several insecticides can be effective in controlling armyworms. They often contain active ingredients like bifenthrin, cyfluthrin, cypermethrin, lambda-cyhalothrin, permethrin, or spinosad. These insecticides work by coming into direct contact with the armyworms, killing them, and stopping further damage. When applying insecticides, make sure to follow the label instructions carefully. It’s important to apply the pesticide on dry lawns to ensure maximum effectiveness. After application, avoid irrigation or rainfall for at least 24 hours to allow the insecticide to work. This ensures the maximum amount of time for the pesticide to address the armyworms.

In addition to chemical control, beneficial insects like parasitic wasps can help control armyworm populations. These natural predators parasitize armyworms, helping to reduce their numbers without harming your lawn. Consider encouraging beneficial insects in your garden as a long-term solution to armyworm control.

Prevention and Recovery: Tips for an Armyworm-Free Lawn

Regular lawn inspections are essential to prevent armyworm infestations. If you spot armyworms or signs of damage early, take immediate action. Consider using preventive treatments if your area is prone to armyworm outbreaks, particularly during summer.

Recovery Post-Infestation

Fortunately, armyworm damage is typically limited to the grass blades, and the plant crowns, which are the critical part of the grass plant, are not harmed. This means that recovery is possible with proper care.

Watering

Watering and fertilizing your lawn correctly will encourage grass regrowth after an armyworm infestation. Keep your lawn adequately hydrated, especially during hot, dry weather, to promote healthy recovery. Warm-season grasses, such as bermudagrass, require about 1 to 1.5 inches of water per week, ideally spread over 1-2 watering sessions. This helps the grass establish strong roots while avoiding overwatering, which can lead to other problems.

Fertilizing

Additionally, applying a balanced fertilizer can further support growth, providing the necessary nutrients for the lawn to bounce back. During hot, dry weather, consistent watering and proper fertilization are key to encouraging healthy regrowth and strengthening your grass for future defense against pests like armyworms.

How to Repair Lawn Damage After an Armyworm Infestation

Once the damage has been done, repairing your lawn is the next priority. Warm-season grasses like bermudagrass are more resilient and will usually recover from armyworm damage with proper care. However, in cases of severe damage, they can benefit from some extra steps to help restore the lawn.

One of the quickest ways to repair armyworm damage is by laying down new sod. Bethel Farms offers high-quality bermudagrass sod, which is ideal for areas affected by armyworms. Bermudagrass is known for its dense coverage, drought tolerance, and ability to recover quickly from damage, making it an excellent choice for lawn repairs.

Bermudagrass provides dense coverage, which can quickly fill in damaged areas and help your lawn recover. It’s also highly drought-tolerant and can withstand heavy foot traffic, making it ideal for both aesthetic and practical purposes.

For smaller damage, grass plugs can be a cost-effective way to restore your lawn. These small sections of grass can be inserted into damaged areas, where they’ll establish roots and eventually spread to fill in the gaps.

If your lawn has been affected by armyworms, don't wait to restore it. Visit the Bethel Farms website to explore a wide range of high-quality grass sod, ideal for repairing lawn damage quickly and effectively. Reach out today to get the best grass for lawn restoration.