Besides the flurry of falling autumn leaves, are you noticing flurries of moths or worms on your lawn? According to the experts at Sod Solutions, this is the time of year to guard against the fall armyworm, which is notorious for traveling in small armies that devour lawns and gardens, where they feed on the leaves, stems, and other above-ground parts of more than 300 kinds of plants. Fall armyworms take no prisoners, and annual bedding plants, succulents, and homegrown vegetables are all food for these lawn pests.
The fall armyworm is a hungry, hungry caterpillar that comes from eggs laid by moths on tree bark, house siding, or near floodlights that they swarm to. Luckily for northern homeowners, the eggs don’t last throughout winter, so the moths usually migrate to the southern U.S. states, where the armyworms commonly appear from July through October and after tropical storms and hurricanes.
The University of Florida IFAS describes the fall armyworm as green or muddy brown and up to 1.5 inches long, with a wide, horizontal black stripe running down each side and a light-colored upside-down “Y” marking the head. The moths are usually ash gray with wings about 1.5 inches wide.
Signs of Fall Armyworm Infestation
Fall armyworms aren’t shy and you’ll know if you have an infestation when you see hundreds of them feeding in broad daylight. The moths can lay up to 2,000 eggs that hatch in just two or three days, four or five times each year, so you may find several generations that require ongoing treatment.
Look for them in plants in the grass family, such as coastal Bermuda grass, fescues, rye grass, and blue grass. They will also invade small crops.
Besides actually spotting a fall armyworm or armyworm moth, tell-tale signs of infestation include:
- Small brown patches of lawn
- Chewed grass blades that have a transparent “windowpane” appearance
- Clusters of eggs or fall armyworms near woods, buildings, sheds, light posts, siding, fence posts, tree leaves, or bushes
- Caterpillar frass – moist green fecal pellets – on leaves at the base of plants and grass
How to Prevent and Treat Fall Armyworms
It’s important to go on the attack to prevent and treat armyworms before any damage spreads further. Unlike sod webworms, which cause similar damage, fall armyworms can be difficult to control.
- Mow the lawn regularly to the correct height, no shorter than 2 inches, for your type of grass.
- Reduce the buildup of thatch on your lawn by adding organic materials such as peat moss.
- Lightly irrigate your lawn.
- Aerate your lawn at least once a year.
- Regularly water your lawn with about 1 inch of water each week to prevent it from getting too dry and warm, which armyworms prefer.
- Maintain a proper fertilizer schedule to keep your grass strong and more resistant to damage.
There are many effective insecticides you can apply to treat fall armyworms and the earlier you fight back, the better. Look for insecticide products with bifenthrin, acephate, or chlorantraniliprole.
Don’t surrender to a fall armyworm invasion! By maintaining a healthy lawn to resist damage and treating any lawn pest infestation immediately, you can win the war against fall armyworms.