Armyworm numbers are being reported around the county following recent rain events and slightly cooler temperatures. Armyworms can devastate rangeland and pastures quickly.
Local producers have reported increased armyworm activity in hayfields and pastures over the past week.
Armyworm moths can lay up to 2,000 eggs that hatch in two to three days, according to a report by AgriLife Extension entomologists. There can be four to five generations per year.
Armyworm caterpil-lars can be picky eaters that prefer high–quality, fertilized forage typically found in fields maintained for hay production. They are a common pest of bermudagrass, haygrazer, oats, wheat, ryegrass and other forage crops.
Producers should scout in the morning for armyworms. 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 threshold for insecticide spray treating a pasture is three or more armyworms per square foot. Armyworms in those numbers should be treated immediately. Armyworms in the last two or three days of their larvae stage consume 85 percent of their diet.
Producers should use only insecticides that are labeled for armyworm control in pastures and hayfields, and always follow all label instructions on pesticide use and restrictions.
Don’t wait long if the numbers are at the threshold, because they can do a lot of damage quickly. If you find them in the morning, try to spray that day.
For more information about armyworms call the DeWitt County Extension office at (361) 275-0816.
