When fully grown, fall armyworms are 1.5 inches long. They are always striped, but their coloring is not always the same. Their background color ranges from light green to almost black.

You can identify fall armyworm caterpillars by four black dots on the back of the tip of the abdomen. Larger caterpillars typically have a light-colored, upside-down Y-shape on the head and three white lines on top of the segment just behind the head.

Scouting critical

"The earlier an infestation is detected the better. Young fall armyworms under a half inch in length don't eat much," says Flanders. "As the caterpillars get bigger, the more they will eat, and the bigger they are, the harder they are to control."

She encourages farmers to regularly scout fields now if they have not already begun doing so. She emphasizes that scouting is particularly important with the hot, dry weather affecting most of the state.

Flanders says that using a sweep net is only one element of effective scouting.

"Remember, finding them in the sweep net is the first step. You will need to verify that finding by seeing how many caterpillars you have per square foot. If you find more than 2 or 3 per square foot, the armyworms should be controlled."

Fall armyworms need to be treated when they are still small — no more than 0.5 to 1 inch long. Detecting infestations when the caterpillars are small gives more time for control measures to be implemented.

She also points out that fall armyworms will attack bermudagrass lawns as well as bermudagrass pastures and hay fields. Homeowners with bermudagrass lawns should scout their grass for these pests just as a farmer would.

More resources

Farmers and others can get more information on the biology and habits of fall armyworms in Alabama Cooperative Extension publication ANR-1019, "Management of Fall Armyworms In Pastures and Hayfields," available online and from county Extension offices.

The interactive map link is also the place to see who has a sweep net. Cross-hatched counties are counties where cattle producers have sweep nets. Most county Extension offices also have nets.

Producers can learn to use a sweep net in this Extension YouTube video.