By Emmy Powell
Communications Specialist

Recent rains and cooler temperatures have been a welcome relief across the state, but they’ve also brought an unwanted pest—armyworms.

Texas A&M AgriLife Extension Service experts encourage farmers and ranchers to scout their fields frequently to prevent widespread damage.

Areas receiving rain will see grass growth that could fuel armyworm populations. If producers aren’t proactive in treating fields, armyworms can cause significant damage to pastures and rangeland, which is problematic for cattle operations dealing with short hay and forage supplies due to drought.

“Armyworms can be picky eaters,” Dr. Vanessa Olson-Corriher, AgriLife Extension forage specialist, said. “These insects are going to select well-fertilized or irrigated forages to feed on.”

Winter wheat, annual ryegrass and other small grains have been found to be at higher risk of armyworm infestations.

Scouting for armyworms helps understand how to manage any infection. Ranchers are encouraged to look for armyworms that are green with brown or black patterns and are identified by the white inverted Y on their heads.

“After a rain, producers should walk through their fields at dawn, when armyworms are most likely to be active and see if the population size warrants treatment with an insecticide,” Corriher-Olson said.

AgriLife experts advise ranchers to treat forages that have more than three armyworms per square foot.

“If an armyworm infestation is detected, it’s important to treat it quickly,” Tracy Tomascik, Texas Farm Bureau associate director of Commodity and Regulatory Activities, said. “It’s also recommended to keep insecticide on hand to treat any infestations throughout the fall.”

If not treated immediately, they could ruin an entire field overnight, he said.

“This year has been mostly dry, so the armyworm population may not be as high,” Tomascik said. “Recent rains can encourage the rise in armyworm infestations, so it is important to be on the lookout.”

Recent AgriLife Extension reports note that ranchers in East, West Central, Southeast and South Texas have noticed larger populations of armyworms.