Armyworms: The Marching Menace

It’s summertime in Georgia, which means two things: heat and humidity. With heat and humidity come insects and pests, and one of the most destructive among them is armyworms. Armyworms will feed on vegetables and other plants, but their favorite food source is turf grass.

That’s right: armyworms are eating your lawn.

Heavy infestations of these pests can decimate lawn grasses in just a few days, so we’re going to help you identify them, know how to spot signs of damage and provide tips for how to control them before they eat everything in sight.

How Do I Identify Armyworms?

Before we get into the entomology of the type of insect you’re dealing with, it’s important to know what to look for in terms of damage. The first sign of armyworm destruction often occurs at the tips of grass blades, giving them a transparent “windowpane” effect due to plant cells being eaten. Small brownish patches on your lawn – similar to drought stress – are another indication that you might have a problem. Armyworms are voracious eaters, but they’re also rather picky. They prefer to eat just the soft green layer of turf grass and sometimes leave individual blades ragged and half-eaten. This leaves your lawn with a patchy appearance.

However, if armyworms are present in sufficient numbers, the competition for food resources means they’ll be less choosy – and more destructive. A heavy infestation can lead to your grass being sheared to the ground, with nothing left but dirt and creeping runners. Healthy bermudagrass can typically recover from this type of defoliation, but newly-established ryegrass or fescue can be stunted or even killed outright.

Because you want to find and halt an infestation before it gets to that point, you need to be able to recognize the enemy.

What Is an Armyworm?

Eventually, an armyworm will turn into a moth. During the larval stage, however, the caterpillar army can cause rapid, significant damage to certain agricultural crops as well as turfgrass. Feeding primarily on bermudagrass, ryegrass, fescue, and bluegrass, they’re the most common cause of insect damage to golf courses, athletic fields, and home landscapes. The presence of electrical lights around many of these settings draws the adult moths, and they tend to lay their greenish-white eggs on the undersides of leaves and various structures near the turf. This ensures the larvae have a plentiful food source after hatching, which is thoughtful of them as parents, but problematic for those of us who don’t want a decimated lawn.

Ranging in color from shades of greenish-brown to almost black, armyworms feature alternating yellowish and dark brown stripes on each side. They reach 1.5-2 inches in length at larval maturity and derive their name from their tendency to move in formation as they eat their way across backyards and ballfields.

How Do I Get Rid of Armyworms?

Now that you know what you’re dealing with, the most important question remains: how to get rid of them.

An ounce of prevention is worth a pound of cure, so learning to identify armyworm eggs and treat them before they hatch is the ideal proposition. However, most of us lead busy lives, so skulking around the edges of the lawn and checking out the undersides of leaves on bushes isn’t always practical or possible.

If you have discovered an active armyworm infestation, it’s important to treat it before it gets out of hand.

Armyworms are crepuscular, which means they are most active in the early morning and late evening, although you can find them munching on your lawn at almost any point during the day. However, treatment is most effective during times of high activity, so it’s best to apply insecticide at dawn or dusk. There are several different delivery forms to choose from:

  • Granules: Use a lawn spreader to ensure even coverage, and then water the granules immediately after to activate them. This works on armyworms both above and below ground and offers protection for a period of up to three months.
  • Ready-to-Spray: This type of insecticide comes in a bottle that attaches directly to your garden hose. It kills armyworms on contact and continues to prevent reinfestation for up to three months.
  • Ready-to-Use: This option works for spot treatments and very minor infestations, killing armyworms on contact.

Questions? Contact Us

If you’re still unsure what to look for, need recommendations for the most effective insecticide brands, or would rather have the services of a professional in addressing your armyworm problems, click here to drop us an email, or call us at (770)-913-9033.