Army worms are back in the Mid-Columbia

Annette Cary, Tri-City HeraldOctober 19, 2013 

Army worms are back this fall, slithering into homes, damaging lawns and eating hay crops.

It's not as bad as the infestation that cleared store shelves of pesticides in the Tri-Cities in the fall of 1998. But there appear to be more of them than usual, according to a local entomologist.

"They are really disgusting," said Kathy McCaddon, of Richland, who has been finding the caterpillars in her house, her mailbox and her yard for the past 10 days. They are dark colored with lengthwise stripes and can grow up to about an inch and a quarter long.

People are bringing the army worms into the Washington State University Benton County Extension Office for identification and advice, said Eileen Hewitt, a Master Gardener. And Tim Waters, an entomologist and director of the WSU Franklin County Extension Office, said he's been getting calls about the army worms feeding in hay fields.

"I see army worms. There are a lot of them," he said during a cellphone call with the Herald late Friday afternoon as he walked through his pasture. It's easy to spot damaged leaves, he said.

He'd seen 20 to 30 crows in the pasture earlier eating the army worms, but a whole lot of the caterpillars were left.

They are called army worms because they feed together and move as a group to find new sources of food, according to information from Marianne Ophardt, who has been writing columns for the Herald during infestations for more than two decades. She is a horticulturist for WSU Benton County Extension.

Heavy infestation years are sporadic, sometimes happening two years in a row and sometimes not again for eight years.

Some years there can be three generations of army worms, with eggs laid by brown moths, or millers, hatching into larvae that feed in September and October. They are the ones that are noticed as crops or weeds mature and the caterpillars crawl out of the fields into yards and gardens looking for food, Ophardt said.

As temperatures drop, they will go into a resting stage in the soil to hatch as moths in the spring.

Farmers need to scout their fields and consider treating for them, Waters said. They're mostly in hay now, which is green, but also could be an issue for winter wheat.

McCaddon has brown spots on her lawn, where the army worms have feasted, but she generally sees them only at night outside.

Inside, she found one in her dishwasher. And when she reached into her mailbox one fell out onto her hand after leaving a trail of green slime across an envelope, she said.

Worms that have crawled inside the house likely will dry out and die rather than hatch, according to information from the extension office. They're best handled by just throwing them away and if there a lot of them, caulking around door or window frames or sealing up other entry points, according to information from Ophardt's columns.

Army worms only should be controlled when they infest in large numbers and when damage to lawns or gardens is excessive, according to the office.

Pesticide is best applied in late summer and now they should soon be slowing down with cold night temperatures and frost and disappearing into the soil.

-- Annette Cary: 582-1533; acary@tricityherald.com; Twitter: @HanfordNews

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