Posted on April 19, 2025 by Lawn Doctor
Does something seem to be eating the tips and edges of the grass blades in your yard? You could be dealing with armyworms. They’re destructive pests that are actually caterpillars on their way to becoming moths. When you discover an infestation, its best to act quickly to avoid having your entire lawn destroyed.
Armyworms are moths in their larval stage. They earn their name based on the way they move across your lawn like an army and eat all the grass blades in their way. Southeastern states tend to sustain the most damage from armyworms, but these pests are found in all states east of the Rocky Mountains. There are different varieties of armyworms, including fall, yellow-striped, beet and true armyworms. In many areas, it’s the fall armyworms that most commonly destroy grass blades.
Armyworms are active later in the evening and into the night, so you probably won’t catch a glimpse of them during the day. They can range in color from black to greenish-brown with a smaller yellowish-brown head and stripes along the abdomen that are orange, white or brown. However, the coloring may vary based on the type you have. For instance, true armyworms are typically tan while fall armyworms appear gray. The pests are about 1-1/2 inches long when fully grown.
You might be more likely to identify the problem by the damage they leave behind. It often starts as a small brown patch that grows quickly.
The grass that covers your yard is the main feature that attracts armyworms. The adult moths lay their eggs near food sources, which include turfgrass. Armyworms aren’t picky — they eat most types of grasses as well as crops and fruit trees.
However, they may be more likely to choose yards with long grass, lots of weeds or lawn debris. Those features serve as protection from natural predators for the eggs and larvae. Wet conditions may appeal to armyworms, so be cautious if drainage issues keep your yard damp.
Damage from armyworms often becomes noticeable later in the summer. In the beginning, it might look like drought damage. When armyworms are in the lawn, the grass tends to change colors and may lie flat. If you look closely, you might notice that the tips of the grass blades are chewed or that the edges look ragged.
It doesn’t take long for armyworms to complete their destruction, especially if you have a major infestation. They can destroy an entire lawn in just a few days. The grass turns brown, and you could end up with dirt patches in your lawn.
Insecticides are often the fastest and easiest way to get an armyworm infestation under control. Products that typically work include those containing ingredients such as bifenthrin, permethrin and cypermethrin. You may be able to use Bacillus thuringiensis for a more natural treatment for armyworms if you catch the infestation early. It only works on younger caterpillars, so it won’t kill full-grown armyworms in your yard.
Leaving the pesticide application to the professionals often gives you better results. Pest control companies can use commercial-grade chemicals that aren’t available to homeowners. At Lawn Doctor, we know when and how to treat armyworms properly.
Eliminating the areas in your lawn that are attractive spots for moths to lay their eggs could help prevent an armyworm infestation. Keep your lawn mowed regularly, and clean up any lawn debris. If you haven’t dethatched your lawn in a while, doing so could help with armyworm prevention by removing the debris that shelters the caterpillars. Getting weeds under control may help. If you have wet areas in your yard, consider ways to improve drainage.
Natural predators of armyworms can also help keep populations under control. Ladybugs and lacewings are helpful insects that you can purchase and add to your garden. They eat the eggs, keeping armyworms from emerging. Parasitic wasps are also ideal for natural pest control since they eat many types of garden pests, including armyworms, but they’re not harmful to humans. Attracting birds to your yard is helpful since they eat armyworms at all stages as well as other pests that could damage your lawn.
Keep an eye on your lawn regularly to look for early signs of an infestation before large numbers of armyworms take over. The adults typically lay larger clusters of eggs together, so you can check plant bases and the undersides of leaves for clumps of eggs. A quickly growing brown area in your yard could also indicate a problem.
At the first sign of an infestation of armyworms in your yard, call Lawn Doctor for treatment options. Our pest control solutions protect your yard from armyworms and many other pests to keep your grass looking pristine. Contact us today to learn more about how we can help.
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