Recently lawns in the Burleson area have been plagued by Armyworms.

“The Armyworms are hitting turf grasses, coastal Bermuda and newly planted wheat and oats right now,” said Dr. Charles Allen, Professor, Associate Department Head and Extension Entomologist at the Texas A&M AgriLife Extension Office.

According to Allen, Armyworms are very small (1/8 inch) at first, cause little plant damage and as a result often go unnoticed. Larvae feed for two-three weeks and full grown larvae are about one to 1 1/2 inches long.

Given their immense appetite, great numbers, and marching ability, fall Armyworms can damage areas in a few days,

Allen said reports of damage are streaming into his office and to colleagues across the state.

The damage isn’t just to lawns, Allen said. Farmers and stockmen are reporting damage to grass and early wheat planted for grazing.

“The fall Armyworm, all too familiar to many producers, is the primary culprit,” Allen said. “During warm weather, the caterpillar stage lasts about 14 days, but eats about 80 percent of its total intake during the last three or four days. That’s when the worms are at their largest and can do the most damage to a crop. It’s also when huge numbers of them can transform a field from a thing of beauty to a severely damaged nightmare seemingly overnight.”

The caterpillar has broad bands down its body and a light colored inverted “Y” on its head. It also has some raised dark spots along with a few black hairs down its back.

“They are not picky eaters,” Allen said. “They have a wide range of host plants which include, but are by no means limited to pasture grasses, corn, grain sorghum, rice, wheat, turf grass, and even weeds and landscape plants as well.”

Moths are active at night when they feed on nectar and deposit egg masses. A single female can deposit up to 2,000 eggs and there are four to five generations per year, according to Allen.

The fall armyworm apparently does not overwinter in north Texas, but survives the winter in south Texas. Populations increase in south Texas in early spring and successive generations move northward as the season progresses.

The adult moth has a wingspan of about an inch and a half, with mottled gray forewings and light colored, translucent hind wings, Allen said.

“Unlike the seemingly indiscriminate diet of the caterpillars, the female moths can be pretty selective about where they lay their eggs, opting for only the best, most productive pastures and crops for their future brood to flourish in,” Allen said. “However, wet weather can bring on exploding populations like we are currently experiencing. During these outbreaks, ‘housing shortages’ can occur so moths may lay their eggs on just about any available host plant.”

Allen said the eggs are laid in clusters and covered with light-colored wing scales. Adult moths typically live 10-21 days, during which females lay 1,500-2,000 eggs — mostly in the first half of her adult life.

“It’s also important to note that fall Armyworms are great travelers,” Allen said. “Their long-range flight takes many well into Canada each year where they feast on crops, grasses and weeds. But whether they feast in Canada or Texas, cold weather eventually zaps them as they can’t survive latitudes through the winter that are much farther north than South Texas and southern Florida.”

“When two to three Armyworms longer than half an inch are found per square foot, it’s time to take action as forage losses can be prevented by using an insecticide,” Allen said. “As with scouting, insecticides will be most effective if applied when the worms are actively feeding on host plants in the early morning or late evening.

As far as what to spray, Allen recommends pyrethroid insecticides as they are relatively inexpensive and are normally an effective option for fall Armyworm control in wheat, Coastal Bermuda grass and other hay and pasture crops.

Steve Byrns from the Texas A&M AgriLife Research and Extension Center at San Angelo contributed to this article.

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