About this time every year wide swaths of territories in Oklahoma are attacked by an infestation of armyworms – also known as cutworms.
Technically, they are classified under the genus Spodoptera and are a type of moth.
This species will feed on a very wide variety of plants but prefer grasses.
You may see them singly or in great numbers on your sidewalks and driveways as they squirm their way through your lawns and gardens.
An OSU report says an infestation in turf can be detected by applying irritants such as dish detergent. Add one-quarter cup of dry or one ounce of liquid detergent to one gallon of water in a sprinkling can and apply the solution to one square yard of turfgrass where an infestation is suspected.
Also effective is mixing one tablespoon of a commercial garden insecticide containing 1 percent to 2 percent pyrethrin in one gallon of water. If the thatch is dry, irrigation before the test is advisable.
The caterpillars will surface within 10 minutes of soaking and can be found by separating the blades of grass. Treatment may be needed when 5 to 10 larvae are found per square yard of turf.
According to the OSU report, the Fall armyworm does not overwinter in Oklahoma. It reinfests the state each year by moths that migrate northward from the Gulf Coast, Texas, or Mexico.
Migrating populations usually reach Arkansas and Oklahoma by late June.
Each female lays about 1,000 eggs in masses of fifty to several hundred.
Larvae are present by early July. After feeding for two to three weeks, larvae dig into the soil to pupate.
A new generation of moths emerges about two weeks later. There are several overlapping generations extending into October or even November in some years.
This species will feed on a very wide variety of plants but prefers grasses. Most turfgrasses are subject to infestation.
Fall armyworms are potential turf pests in late summer and fall. Large numbers can consume all aboveground plant parts, and they are capable of killing or severely retarding the growth of grasses.
This species may migrate in large numbers in search of new areas in which to feed. Moths are attracted to lights and may lay masses of eggs on non-host plants, walls and clothes on lines.
Timothy Whitt, the Founder & Chief Executive Officer of The Pied Piper based in Eufaula, says if you have had armyworms this year, you are likely to have them again next year.
“It’s a seasonal problem and you usually find repeat problems,” Whitt said. “Some years are worse than others.”
If your normally lush green lawn is developing patches of drought-like brown spots, it could be you have an armyworm problem.
With treatment and care, the lawn should return to its previous healthy condition.
“Water and fertilize it and it should come back,” Whitt said.
He warned about applying fertilizer this time of year. It may be too late going into fall.
“Be cautious about fertilizing Bermuda grass,” he said.
Whitt said most homeowners don’t have the proper equipment, especially protective gear.
“And many don’t have time to do it. It takes a lot of time.”
He said you don’t want to mow an infested lawn every week. You need to let it rest. Change your mowing rotation.
He said ultimately the lawn isn’t going to die completely.
“It will recover, and it will be fine,” he said.
