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What's Destroying North Texas Lawns? An Armyworm Invasion

Updated: Feb 14, 2022

If you have a lawn, you’ve probably been witness to this September's plague of Armyworms marching across North Texas lawns. These pests – also called “sod worms” – thrive on Bermuda, St. Augustine, and Fescue grasses, eating the blades down to the ground and leaving you with a dead lawn. (Interestingly they don’t like Zoysia, so if you have this type of grass you should escape the devastation.)

The Armyworm is a caterpillar that develops into the Armyworm Moth. A few Armyworms don’t usually do much harm. It’s actually pretty common to have a few in our lawns most of the time. Armyworm eggs and larvae are also sometimes transported from one part of the state to another on grass sod intended for residential and commercial turf, or they can migrate here from warmer areas to our south.

A Fall Phenomenon

They are usually more noticeable in the fall, lurking between blades of grass. But this year, our early September rains have brought them out in record numbers, and at their current population levels, they can devour your entire lawn in a very short period of time. Texas A&M’s Aggie Turf site notes that it is important to treat as soon as possible to avoid further injury.

Several different species inhabit North Texas, so yours may look slightly different from your neighbors, but there’s no question they are a problem.

Organic Products

Fortunately, we have organic solutions you can use to eliminate them effectively and safely without harming children, pets, or the environment.

One very effective product is Thuricide. Thuricide is a highly specialized bacterium called Baccillus Thuringiensis kurstaki (BTk). It is a soil-borne bacterium that only affects caterpillars. Once the Armyworm larvae ingests the BTk, the bacteria works to stop feeding until death occurs. It does not affect birds or beneficial insects (bees, green lacewing, ladybugs, etc.) when used as directed.

Another more generalized product is Spinosad. Spinosad is also a natural substance produced by another bacterium in the soil that can be toxic to insects. Spinosad affects the nervous system of insects that eat or touch it. It causes their muscles to twitch uncontrollably, which leads to paralysis and ultimately their death, typically within one to two days. Spinosad is used to control a wide variety of other pests as well including thrips, leafminers, spider mites, mosquitoes, ants, and fruit flies.

Both products need to be reapplied every 7 to 10 days, or after a rain. Because they are both live bacteria, mix only enough for a single treatment.

Instructions for Baccillus Thuringiensis

Mix 2 oz. per 3 gallons of water, which make enough to treat up to 1,000 square feet. Apply to all plant foliage. Repeat applications weekly to maintain control of pest insects.

Instructions for Spinosad

Mix 2 oz. (4 Tbsp.) per 1 gallon of water. Mix thoroughly and apply uniformly to both upper and lower surfaces of plant foliage.


Armyworms are prolific and responsive to favorable conditions. Each generation of eggs hatches in 5-10 days, and the tiny caterpillars grow fat as they feed. When full grown, they burrow into the soil to pupate, then emerge as adult moths. The adults mate and lay eggs, thus starting the life cycle over again.

Anywhere from three to six generations hatch out each season. Just when you think you’ve gotten rid of them another generation is preparing to leave the soil to replace them! And most North Texas winters are warm enough to allow Armyworms to overwinter as eggs and pupae beneath the soil.

Your fall lawn care program should include taking a close look at your turf to inspect for this devastating pest. Then be prepared to take quick action to prevent them from ruining your beautiful lawn.


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