Armyworms invading Texas lawns & pastures following heavy rains

Armyworms invading Texas lawns & pastures following heavy rains

Hay and forage producers and homeowners around the state are battling armyworms following rains and cooler weather, according to Texas A&M AgriLife Extension Service experts.

The fall armyworm is a common pest of Bermuda grass and many other crops in Texas,  said Vanessa Corriher-Olson, AgriLife Extension forage specialist, Overton. Given their appetite, numbers and ability to move, fall armyworms can consume entire fields or pastures in a few days.

Armyworm caterpillars are picky eaters that prefer high-quality, fertilized forage typically found on lawns &  fields maintained for hay production or pasture, she said. They are a common pest of Bermuda grass, sorghum, corn, wheat, rye grass and many other crops in north and central Texas.

Homeowners & farmers should scout each morning for armyworms, she said. Armyworms are night feeders that try to avoid daytime temperatures.

Armyworms are green, brown or black in color and can be identified by the white inverted Y on their head. They can grow up to 1 inch in length when mature. The pest got its name because they appear to march across hay fields, consuming the grass in their path.

The key to managing fall armyworms is frequent inspection of lawns & fields to detect infestations, she said. Armyworm moths can lay up to 2,000 eggs that hatch in two to three days, according to a 2018 report by AgriLife Extension entomologist Dr. Allen Knutson, based in Dallas. There are four to five generations per year.

The threshold for insecticide spray treating a pasture is three or more armyworms per square foot, Corriher-Olson said. Armyworms in those numbers should be treated immediately because armyworm caterpillars consume 85 percent of their diet in the last two to three days of their larvae stage.