Mike Bernd navigated his way down a hill behind his home atop Casper Mountain, weaving through a mix of saplings and century-old trees before stopping at one.

"It's a shame; this is a really beautiful tree," he said, explaining how he would fell the tree and dice it up next year. "It's probably more than 100 years old, if you were to bore in and count the rings."

The tree, about 18 inches in diameter at breast height, is one of a dozen near his home that are infested with beetles this year. There's a small stand of younger trees, none more than 5 feet tall, just paces from this tree.

The large tree is dead, killed by beetles that have nested in it. Dropping it next year will pose a risk to younger trees in the area.

A burgeoning bark-beetle population on Casper Mountain is posing an increasingly large threat to the forest there. Experts have described the problem as an "epidemic."

The beetles lay their eggs under the bark and transmit a blue fungus that clogs tree tissue responsible for water retention. Six to eight months later, the trees die of thirst.

The eggs grow and hatch over the winter and, by the end of the summer, begin a massive migration from their place of birth to a new forest, seeking trees in which to lay their eggs. They die and a new brood hatches, starting the cycle over again.

That process is part of a natural forest cycle, said Les Koch, a forest health specialist with the Wyoming State Forestry Division. The beetles have been around for centuries.

"[The beetles] do provide a benefit by taking out older, more mature trees to provide for the later regeneration of a new forest," Koch said. "Right now they're at a level that is considered an epidemic when they're taking out trees of sizes that they haven't in the past, and that's created a problem."

The pine beetles affecting trees near Casper could wipe out between 80 and 90 percent of the pine trees on Casper Mountain over the next five years, warned Sam Weaver, president of the Casper Mountain Forest Stewardship Association.

Aside from damaging the look and diminishing the recreational value of the area, the beetle kills pose a major fire risk, Weaver said.

Koch downplayed that 80 to 90 percent number, saying it might be a bit high, but did note the dire nature of the problem.

Weaver said that traps placed on Casper and Muddy mountains have shown a huge increase in the numbers of beetles making the annual flight from trees where they were born to trees where they will lay their eggs.

"The first week in August we had an average of 200 beetles in each of the traps, and in the third week that jumped to more than 800 on Casper Mountain and as much as 2,000 in one trap on Muddy Mountain," Weaver said. "What we're seeing is, as a result of that flight in August, is an eight or 10 times increase in the amount of new trees infected compared to last year."

The beetles favor trees more than 80 years old with trunks greater than 10 inches in width. That's a significant portion of the trees on Casper Mountain because of how old the forest is, Weaver said.

When the trees die, they dry up and turn into kindling. A tree here and a tree there isn't so much the problem, Koch said, but large areas of infected trees become fire hazards.

"Once the trees fall, they provide more jackpots for forest fires to ignite, and of course you have more 'down woody fuel,'" Koch said. "People need to clear out the fuel and excess growth creating fire hazards. People are going to have to be more wary of the beetle kill and the relationship to fire."

Beetle infestations are being reported in evergreens across Wyoming and the West. Casper Mountain presents a unique challenge because it's not within a national forest and about 65 percent of the land is owned by private citizens, Weaver said, so the responsibility is on the individuals to protect their homes and land from the infestations.

Weaver said some of the mountain's residents have taken to cutting down infested trees and making piles that they cover with thick plastic, preventing the beetles from spreading.

Bernd pointed to a small tree that had been bucked and wrapped in plastic, and nailed closed.

"The moisture you can see under the plastic, that's a good sign, it means it's heating up in there," he said.

The beetles that would hatch and eventually make flight next summer are steamed inside of the plastic, killed by the heat. After a year or so of being covered, the wood can be split for firewood or milled for commercial use.

Koch was optimistic, saying the situation would sort itself out -- as the beetle population grows, the beetles seek smaller trees. At some point, the trees that are left won't be able to support the previous year's population growth.

"The trees won't be big enough to sustain a brood, and they'll die off. That's what's going to happen," Koch said. "They'll run out of hosts."

You can reach city reporter Pete Nickeas at pete.nickeas@trib.com or (307) 266-0639. You can read more about Casper politics and government at http://tribtown.trib.com/redtape.

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