Friday, May 18, 2012

Evergreen bugs are back

Pine needle scales attacking local spruce trees

Express Staff Writer

Arborist Bill Josey shows examples of pine needle scale bugs near Ketchum this week. Photo by David N. Seelig

Evergreens in the Wood River Valley are suffering from another outbreak of pine needle scale, an infestation of small insects that suck water and nutrients from the needles of evergreen trees, causing the needles to turn brown and die.

The scales, or egg containers, can be identified as small white dots that attach to the needles.

Arborist and Hailey Tree Committee Chair Bill Josey said that when the scales hatch, sometime in mid-June, numerous bugs will emerge to attack spruce and other coniferous trees in the valley.

Josey said 40 to 100 bugs can hatch out of one white scale, crawling from branch to branch and tree to tree. He said that in some cases, an infected tree can lose all its needles, turn gray or brown and become subject to other pests in its weakened condition.

"It's an epidemic," he said.

According to a U.S. Department of Agriculture website, in the wild areas of Idaho, pine scales infect lodgepole pines, ponderosa pines and other evergreen trees. In the Wood River Valley, the bugs can be found in many places along Sun Valley Road heading toward Trail Creek.

"The older neighborhoods in Ketchum and Sun Valley, with the oldest trees, are sometimes getting it the worst, but it's also exploding throughout the entire Wood River Valley, including Hailey and Bellevue," Josey said.

Natural predators include a minute ladybug and several species of parasitic wasps, which Josey said are not plentiful enough in the valley to keep the scales in check.

Josey said treatments for pine needle scale include the use of systemic insecticides, contact sprays or a combination of both. He said treating pine needle scale can cost from $40 to $100 per tree, depending on the size of the tree and extent of the infestation.

"Treatments work well, but scales are very hard to control," he said. "We're looking at management, rather than eradication of pine needle scale."

Tony Evans:

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