A bagworm clings to an evergreen tree in downtown Lawrence on Tuesday, August 19, 2008.

Sunshine illuminates webworms clinging to a tree in East Lawrence.

Picking bagworms from trees can be a tedious task.

But overlooking just one “bag” can mean leaving hundreds of bagworms on a tree.

Female bagworms lay about 1,000 eggs in each of those bags, according to Roger Boyd, professor emeritus at Baker University in Baldwin City. He also is tree board chairman in Baldwin City.

“If you don’t pick any, they tend to build up,” Boyd said.

And, he noted, the insects are cyclical. They increase in number from year to year, then die off unexpectedly.

“No one seems to know and they crash and start over,” Boyd said. “They’re worse this year because they had a good year last year.”

The insects create protective bags, each about an inch and a half long. Inside, the females lay eggs and the males transform into moths, according to Jennifer Smith, Douglas County horticulture agent with Kansas State University Research and Extension.

Although Boyd, who cares for trees on the Baker University campus, reported an increase in bagworms in Baldwin City, Smith said she hadn’t noticed an increase this season.

Bagworms feed primarily on cedar trees and some pines, but they’ll also target deciduous trees.

Boyd suggests Orthenex as an insecticide that can be purchased locally to combat bagworms. Although the ideal time of year to spray is in the spring, Boyd suggests picking off as many bags as possible from the tree now.

Smith and Boyd agreed that spraying does little good this time of year.

“About the only thing they can do is pick them off and that will actually help reduce the population,” Smith said. “The insect is protected by that bag so there’s no point in spraying.”

In Tonganoxie, tree board chairman Velda Roberts reported “a total infestation” of bagworms this season.

“They’re just hitting every kind of tree,” she said. “I’ve never seen anything like it.”

Roberts recommends putting the bagworms in kerosene or diesel fuel. She cited an instance in which a woman picked the bags and then put them in a garbage can in her garage. The next morning, all of the worms had escaped and taken over the garage ceiling. Boyd suggests simply putting the insects in a tightly sealed bag before disposing of it.

Webworms different

Smith said she receives many calls about what people think are bagworms.

In reality, they are webworms. Many trees in the area look as though spiders have been busy spinning high-density webs, but it’s actually the work of webworms.

Boyd said webworms are mainly a nuisance, as far as appearance, but they rarely kill a tree. Any limb with damaged foliage normally will return healthy the next year. Webworms usually feed on walnut trees, but other trees are also fair game.

Boyd said cars should not be parked under limbs covered in webworms because the insects release a sticky substance that is difficult to wash off.

Pine bark beetles

Scotch and Austrian pine trees are taking a hit this season because of another insect: the pine bark beetle.

The pine bark beetle is a species of mite.

Boyd said there’s not much that can be done to save the infected trees.

“As soon as they turn brown,” Boyd said, “they might as well cut them down.”