ENTERPRISE, Ore. — After a devastating attack on hay crops last fall by armyworms, Wallowa County farmers and crop scientists are taking measures to see that they don’t get hit again.

Darrin Walenta, an agronomist with field crop responsibilities for Wallowa, Baker and Union counties for Oregon State University Extension, said they are placing traps that contain pheromones of the female armyworm moths in likely hot spots around the region. The scents emitted by the pheromones will attract male armyworms to the traps and data can be collected from them.

“If we can collect data all season long, it’ll help predict … when the population will hit peak activity levels,” he said.

Walenta said he expects to be setting the traps in late May or early June.

Walenta said the armyworm moths migrate from the Southwest, often from Texas. They lay their eggs, which hatch into worms. They go into a pupa stage that become a larva that again pupates and emerges as a moth capable of laying eggs — restarting the cycle. It’s during that second larval stage that the worms become destructive.

And that’s when they need to be taken out, Walenta said.

“That’s when populations reach epidemic levels,” he said.

That’s also when “control measures” are applied. This controls include cultural controls, such as farmers adjusting their harvest dates, or the application of insecticides. Walenta said OSU prefers to use the cultural controls rather than insecticides.

Two types of moths

Pete Schreder, OSU Extension’s livestock range and natural resources agent for Wallowa County, said that of the two recognized types of armyworms, there is the “true” armyworm, which generally attacks in late spring, and the fall armyworm, which attacks in late summer and early fall.

“From visual and expert opinion, it looks like the fall armyworm,” he said.

Walenta and Schreder said the migratory nature of the worms’ moths works in the favor of Northeast Oregon.

“Obviously there was a negative impact, it’s just hard to measure at this point across the county,” Schreder said. “We’re hopeful that based on a colder winter, it will impede the infestation.”

He said it’s primarily grasses the worms are going after; they avoid dry wheat and legumes. Thus, with the widespread wheat crops now dry and being harvested, they don’t provide tempting targets for the worms.

“They seem to like the fresh, green growth in the timothy,” he said. “They prefer the young, tender growth on timothy and irrigated grass pastures.”

But it’s more than just timothy grass. Wallowa County Commissioner Todd Nash brought up the subject at a commissioners meeting in September, saying he’s done some research on the worms.

“There are about 240 different species of grass they’ll go for,” he said.

Schreder said the worms gobble up the crops quickly.

“Basically, they defoliate them. They eat the leaves, strip the leaves,” he said. “And they do it in a hurry.”

Extent of damage

Schreder said officials never did get an accurate estimate of the extent of the damage from last fall’s attack.

“They’re everywhere,” said Scott Shear in September, who farms near Joseph.

Dan Butterfield, who runs Butterfield Farms near Joseph, said his farm got hit hard, but the attack just forced him to cut sooner.

“We could find armyworms everywhere we looked,” Butterfield said. “We were fairly well into our harvest, so we just accelerated our cut.”

He said this month that he lost all or most of 80 acres in two adjoining fields. Normally he cuts about 50 acres a day, but because of the urgency created by the worms, he ended up cutting 220 acres in two days and cut three days early.

“We cut everything,” he said. “There was the option to cut or to spray, so we cut.”

He said the spray option came with a drawback in that after spraying, a farmer must wait seven days before harvesting. Also, he said he’s heard that spraying is only moderately successful.

“It doesn’t get all of them,” he said.

Butterfield said his brother, Mark Butterfield, president of the Wallowa County Hay Growers, also got hit hard and cut early.

“He said after three days it was wiping them out so they cut it,” Dan Butterfield said.

Kurt Melville, of Cornerstone Farms Joint Venture and one who reported armyworms last fall, said the attack lasted until the weather froze or the crop was harvested.

“They can’t stand more than a few nights of cold,” he said. “They come up from Texas. When get to the adult stage, they migrate on when it gets cold.”

Like others, Melville isn’t sure if Wallowa County fields will get hit again.

“Won’t know if we’ll have another bad year until weather warms,” he said.

Cornerstone Farms, which Melville runs along with his father, Tim Melville, and brother, Kevin, lost a bit of timothy grass to the worms.

“We had one timothy field impacted about 25-40% lost before I was able to swath it and get it put up for hay,” he said.

He said he would’ve waited to cut, but rains came and reduced the value of the crop.

“Based on conversations with growers, all timothy hay producers experienced some level of damage,” Walenta said.

Hopes for this year

Farmers and scientists are all hoping to avoid a repeat of last year’s unusual event.

Walenta said he’s met with the Wallowa County Hay Growers and Wallowa County Grain Growers, as well as with individual farmers to discuss measures to detect the worms’ presence and ward off another attack.

“We want to avoid the massive levels of damage,” he said, adding that last year was “a situation that snuck in on us and created the massive devastation.”