Armyworms- Identification, Treatment, and How They Ruin Lawns Almost Overnight

lawn decimated by armywormsArmyworms are decimating lawns in the south and west Kansas City Metro areas including Olathe, Overland Park, Lenexa, Paola, Spring Hill and Stillwell. The damage to the lawn pictured was done over a TWO DAY time period! Armyworms have shown up in Spring Hill, Paola, and Stillwell. These pests will eat the grass plant with impressive speed and numbers. ​​Armyworms often infest lawns and crop fields throughout the Southeast, but these pests are spreading to the Northeast and Midwest. Their movement might be linked to a warming climate, Terri Billeisen, an entomologist at North Carolina State University, said, but whatever the reason, be on the lookout for these small worms with voracious appetites. 

Armyworms Are Moving Northward

According to USA Today, an ‘unprecedented’ outbreak of armyworms are destroying lawns across the US, often overnight. “This year is like a perfect storm,” said Rick Brandenburg, an entomologist at North Carolina State University. “In my 40 years, I have never seen the problem as widespread as it is this year.” Brandenburg said armyworms are laying siege to North Carolina but also as far west as Texas and as far north as Michigan and northeastern states, areas that rarely see such significant armyworm populations.

armyworm photo

What Do Armyworms Look Like?

Cutworms and armyworms are larvae of night-flying moths in the family Noctuidae. They both cause damage, but while cutworms are usually solitary feeders, armyworm eggs are laid in masses and larvae will feed as a group which is why the damage is so much more widespread and sudden. Damaged grasses may become withered and brown and with large populations, the appearance of brown areas can happen in 24 hours or less. 

How Do You Know if You Have Armyworms?

The first sign is patches of brown grass. The edges of the grass blades will look chewed and jagged. Sometimes the blades are sheared completely off near the bottom of the plant. Look for larvae in the leaf layer just above the surface of the ground or scratch the surface and they may be hiding just underneath. They do not like the sun, so the best time to find them is in the evening or on a cloudy day. The larvae, or caterpillars, are typically green, brown, or black with a green, yellow, brown, or red stripe that runs lengthwise down their body. They are 1-1/2 to 2 inches long and are not fuzzy like other caterpillar varieties.

How Do You Get Rid of Armyworms? 

There are several ways to treat armyworms. At Heritage Lawns we recommend using earth-friendly methods to keep your lawn healthy. Our Eco-Pride lawn care is designed for long-term solutions for lawns. Here are some eco-wise ways to get rid of armyworms:

  1. Remove them by hand – This is a great solution if your infestation is on the smaller side. Simply pluck the worms from the grass blades in the area and drop them into a bucket of soapy water to kill them. You may want to remove any leftover plants which may help get rid of any unhatched eggs that remain.
  2. Use natural insecticides – If you catch armyworms early (less than 1/2” long) you can try natural insecticides – neem oil and bacillus thuringiensis can work but they can be slow. Use a targeted approach by only treating where you find armyworms and use products that are specifically labeled for caterpillars. This way you don’t accidentally harm beneficial insects. Here are some natural insecticides:
    Neem oil – Spray insecticides are a good choice because these worms are surface eaters so spraying the area should effectively reach them all. Bacillus thuringiensis ​​- This species of bacteria lives in the soil and is poisonous to some insects when eaten (including the armyworm).Pyrethrins – This pesticide is derived from the seeds of some chrysanthemum flowers. Pyrethrins are a mixture of six chemicals that are toxic to insects including mosquitoes, fleas, flies, moths, ants, and of course, armyworms. They work on contact by targeting the nervous systems of insects.
  3. Use Traditional Insecticides – If the caterpillars are over a half inch long, use a traditional insecticide and target the army. You can’t pretreat for them so it only works where you find them. Monitor and use a targeted approach to keep from killing other beneficial insects.

Be on the lookout for armyworms in the Kansas City area. If you think you have them, don’t wait. They can damage a lawn very quickly. If you’d like help treating armyworms or need help with any other lawn care items from weed control to seeding or even shrub and tree care, give Heritage Lawns and Irrigation a call. We think you’ll love our Eco-Pride lawn care system. Call us at (913) 396-6858 or contact us online to learn more, request an estimate, or sign up for a lawn care program.