Spruce Beetles Terrorize Colorado Forests: Officials Say Their Numbers Are On A Rapid Incline

Spruce beetles are terrorizing the forests of Colorado and officials fear that their numbers are on a rapid rise because the damage done by this pest, which is known to destroy forests of spruce trees, is on the rise for a fourth consecutive year, a report from the Denver Post explained.

Aerial surveys were performed on Colorado forests and the results are troubling: infestations were detected on 409,000 acres across the state, expanding onto 182,000 acres of previously unaffected forests. According to a report from Summit County Citizens Voice, since 1996, spruce beetle outbreaks have caused varying degrees of tree mortality on more than 1.5 million acres in Colorado.

Forestry experts agree that the mountain pine beetle, which ravaged more than 5,300 square miles of trees since 1996, is no longer the biggest threat to Colorado forests. A new report on the state’s forests found that mountain pine beetle activity has “subsided and remains low.”

“The epidemic has ended in many areas of Colorado as mature pine trees have been depleted in the core outbreak areas,” the report from the Colorado State Forest Service and U.S. Forest Service said.

The spruce beetle is the most significant natural mortality agent of mature spruce, Barkbeetles wrote. Outbreaks of this beetle have caused extensive spruce mortality from Alaska to Arizona and have occurred in every forest with substantial spruce stands. Spruce beetle damage results in the loss of roughly 333 to 500 million board feet of spruce saw timber a year, the report states.

Recent mapping data revealed that spruce beetles are spreading outward from the San Juans to the West Elk Mountains, the Sangre de Cristo Mountains and into the northern part of the state around Rocky Mountain National Park. The spruce beetle was found to have newly infected 182,000 acres of previously unaffected forests, bringing the number of acres currently impacted to nearly a half million across the state of Colorado.

As spruce beetles numbers continue to rise, they are starting to affect higher-elevation stands of Engelmann spruce. Experts cite the following contributing factors to the spruce beetle outbreak: long-term drought stress, warmer temperatures, and increasing amounts of older, dense spruce.

Speaking on the dramatic rise of the spruce beetle, a representative for GMUG (Grand Mesa, Uncompahgre and Gunnison national forests), gave the following statement.


“Although the preliminary results of the 2015 forest health aerial detection survey indicate fewer new acres were affected in 2015 than previous years, the epidemic continues to spread rapidly in the southern portion of the Gunnison Basin,” spokeswoman Anne Janik said in an email.

However, Janik and other officials noted that Grand Mesa is seeing a drop in spruce beetle numbers.

“It’s been really spotty there,” expained Bob Cain, a U.S. Forest Service entomologist. “It’s so wet up there that (the spruce beetle) behaves a bit differently. It has not taken off like it has in other places.”

As said in a report from the U. S. Department of Agriculture Forest Service, the spruce beetle is one of many beetle species that have recently increased their breeding times. The overpopulation of beetles in some forests in Kenai, Alaska, has led to the destruction of several spruce species that are no longer able to flourish there. The spruce beetle destroyed 2,300,000 acres (2 billion board feet) of spruce forests in Alaska from 1992 to 1999 (about 30 million trees per year at the peak), and 122,000 acres of Utah forests in the 1990s. Outbreaks from 1975-2000 were seen in Montana, Idaho, Arizona, and British Columbia. As of the year 2000, the spruce beetle was responsible for the loss of about 400 million board feet annually, the report concludes.

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