Arctic Science Journeys
Radio Script
1997

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Spruce Beetle-Mania
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STORY: The numerous valleys of Southcentral Alaska should be green with the color of spruce trees this time of year. But instead, the landscape is a stark gray, the color of dead trees. More than a million acres of once majestic spruce trees are dead--felled not by fire or the chainsaw, but by a quarter-inch-long bug.

Skeeter Warner is a forester and entomologist who recently retired from the U.S. Forest Service after 22 years in Alaska. He says Alaska is in the midst of a massive outbreak of spruce bark beetles.

WARNER: "Spruce bark beetle bores through the bark and feeds on the layer of tissues called the cambium, right beneath the bark. These tissues are maybe only an eighth of an inch thick and in there you find the vessels that carry the nutrients that are produced during photosynthesis from the foliage down to the roots, and the beetles get in there and girdle this area."

They also transmit a fungus that grows in the water-conducting vessels of the tree. Eventually the fungus blocks the flow of water from the roots up to the foliage. The tree finally succumbs to thirst.

Spruce bark beetles have always lived in Alaska--clinging to life at the northern-most edge of North America's forests. Outbreaks have occurred in the past, but cool summers and bitterly cold winters that killed beetles kept their numbers in check.

Now scientists say the spruce bark beetle is getting a helping hand from a warmer and dryer northern climate. Typically it takes a spruce bark beetle two years to complete its life cycle, to go from egg to larva to pupa to adult. But the warmer summers have meant that the beetle can go through all four stages and lay new eggs--during just one summer. And that, says Skeeter Warner, means the beetle can reproduce faster and cause even more damage to forests.

WARNER: "The females lay around 150 eggs and then the first larvae hatch within two weeks."

About the only thing that will kill them, short of a massive and expensive effort to rid them using pesticides, is to hope that a severely cold winter will freeze the bugs right in their tracks.

OUTRO: For Arctic Science Journeys, this is Debra Damron reporting from Fairbanks, Alaska.