There are many insects that are native to our southern lawns here on the Gulf Coast. One of the most common and chronic pests in the Southeast is the Armyworm, which is most numerous in the late summer or early fall months. Read more about this insect and how to determine if your lawn has an infestation of armyworms.
How to Identify Armyworms
Armyworms are brown to greenish caterpillars with darker stripes along their sides. Younger armyworm caterpillars tend to be green with dark bands on each side of their body. The lighter midstripe on their backs forms an easily-recognized inverted Y shape where it meets the head. Mature armyworm caterpillars typically reach 1.5 inches in length and turn darker brown before spinning cocoons from which they emerge as light-brown adult moths.
What Does Armyworm Damage Look Like?
Armyworm damage may vary in appearance and severity according to the type of grass and management practices. The damage is often scattered and not confined to dense patches. Populations of armyworms often feed during the day at the same time in the same location and do not rest in a curled position like sod webworms. When armyworm larvae chew away the tender foliage, your grass may seem to thin out and develop brown spots that look burned — a result of the grass plants rapidly dehydrating. For this reason, armyworm damage often closely resembles drought damage. Fortunately, armyworms predominately feed on grass leaves and stems while leaving the roots intact, likely allowing the lawn to recover from the damage.
Treatment for Armyworms
First, identify if armyworms are present in the grass with the soap flush technique. Mix dishwashing detergent at a rate of one fluid ounce per gallon of water for each area you want to inspect. Saturate the first area with this solution and carefully observe the surface for about two minutes. If insects are present, they will crawl to the surface where you can easily detect them.
A population of three or more armyworms per square foot is a reasonable treatment threshold. If necessary, treat your lawn with insecticides while the worms are small. The bigger they are, the harder they are to treat. Consult the product labeling to see if it is effective against armyworms, recommended application rates, and other important instructions and warnings.
Tips for Applying Insecticide for Armyworms
1. Cut your grass prior to treatment to aid in the effectiveness of control so the chemical does not have to penetrate as far to reach the armyworms.
2. Lightly irrigate your lawn prior to treatment, as this may help increase larval activity.
3· Apply armyworm treatments in the early morning or late afternoon when these insects are most active.
If you have any questions, give us a call at any local Woerner Landscape Source!