Archive for Wednesday, August 20, 2008

It’s in the bag: Bagworms produce about 1,000 eggs

Insect feasting on several area trees; Webworm, which does less harm, often mistaken for bagworm

A bagworm, held by Baker University's Roger Boyd, was removed from its bag Monday morning on the Baldwin campus.

A bagworm, held by Baker University's Roger Boyd, was removed from its bag Monday morning on the Baldwin campus.

August 20, 2008

Picking bagworms from trees can be a tedious task.

But overlooking just one "bag," can mean leaving hundreds of bagworms on a tree - literally.

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

"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, and then die off unexpectedly.

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

The insects create bags, each about an inch and a half long.

According to Jennifer Smith, Douglas County horticulture agent with Kansas State University Research and Extension, the worms create the protective bags. Inside, the females lay eggs and the males transform into moths.

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

Bagworms feed primarily on cedar trees and some pines.

"These guys work their way out to the tip and chew the tip of the stem off," Boyd explained. "Pines and evergreens don't have the ability to produce new growth."

But the worms aren't picky, as they also feed on 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. Then, if people still want to spray, they can spray the trees in hopes of eliminating the remaining insects. Boyd said spraying the bags would not kill the bagworms. Instead, spraying the tree helps eliminate the insects because the bagworms feed on the sprayed vegetation and then die.

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 said there seems to be "a total infestation" of bagworms this season.

"They're just hitting every kind of tree," she said. "I've never seen anything like it."

If residents do pluck the cocoons of bagworms from their trees, Roberts recommends putting them in kerosene or diesel fuel.

She said she knew of 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 escaped and had taken over the garage ceiling. Boyd suggests putting the insects in a bag and ensuring the bag is closed.

Webworm work little more than a nuisance

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 - actually the work of webworms.

Boyd said what webworms do to trees is a nuisance, as far as appearance, but they rarely kill a tree.

Although the insects do a number on the foliage on that limb of the tree, the affected foliage normally will return the next year. Webworms usually feed on walnut trees, but do feed on a number of others also.

According to Boyd, tree limbs can be cut down if residents are bothered by the appearance of the webworm-infested limbs.

And cars should not be parked under limbs covered in webworms. The insects release a sticky excretion that is difficult to remove.

Pine bark beetles cause damage

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, and in all there are three diseases killing the pine trees.

Boyd noted there's not much that can be done to save the infected trees.

"As soon as they turn brown," Boyd said about the trees, "they might as well cut them down."


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