Spruce beetle plague moving into Seward area

Posted: Sunday, July 09, 2000

SEWARD (AP) -- The spruce bark beetle has left a trail of destruction across most of the Kenai Peninsula, but so far its impact in the Seward area has been limited.

That's changing, with large numbers of beetles migrating down Kenai Lake to areas south of Moose Pass, according to Ed Holsten, an entomologist with the U.S. Fish and Wildlife Service.

As larvae two years ago, those beetles killed about 2,000 acres of trees between Lower Trail Lake and Crown Point.

This year's warm spring allowed them to disperse in large enough numbers that another 2,000 acres or more will be dead forest by next year, Holsten said.

''There's some really nice spruce stands in the Snow River, and the beetles are just starting to get in there,'' he told the Seward Phoenix-Log.

The voracious bug has killed an estimated 1 million acres of spruce in the last decade, mostly west of the Kenai Mountains.

Holsten and other entomologists hope to head off the invasion using a trick that has stopped beetle attacks on Douglas fir trees in other states.

Last month, they hacked through fields of devil's club to reach untouched spruce stands where the Snow River meets Kenai Lake. Once there, they hung release devices in the boughs of the trees that send out chemical messages telling the beetle to stay away.

Researchers believe the beetles issue the message after they've established a colony of larvae sufficient to overwhelm a tree's defenses. If the tree can no longer produce enough toxic sap to protect itself, the beetles send out pheromones that say ''find your own tree.''

The chemical compound repelled beetles in an isolated test near Cooper Landing last summer, but it has failed in real-life scenarios.

The previous release devices were temperature-dependent and may have been triggered when the beetles weren't in flight, Holsten said. This time, a timed release device should send out a daily signal for two months.

By August, Holsten may have a good idea if the compound worked. Trees that weren't treated should bear the telltale, rust-colored boring dust left by beetles burrowing new nests.

''What we'd like to see is a lot of attacks in the untreated trees and none in the treated,'' he said.

In addition to protecting the trees along Snow River and other pristine spots, the compound could be used in Moose Pass to prevent future losses.

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