Dead mountain pine beetles are displayed by Diann Ritschard in the Routt National Forest in 2007.  The beetles are threatening the existence of millions of lodgepole pine trees in Colorado, and evidence of infestations has been found as far north as Baggs, Wyo., and as far east as Kansas.

File photo

Dead mountain pine beetles are displayed by Diann Ritschard in the Routt National Forest in 2007. The beetles are threatening the existence of millions of lodgepole pine trees in Colorado, and evidence of infestations has been found as far north as Baggs, Wyo., and as far east as Kansas.

A growing epidemic

Pine beetle infestations killing trees in Craig, insects also found as far north as Wyoming and east as Kansas

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— In Craig, pine trees are dying from beetles.

That's what Bill Ekstrom, Colorado State University Extension agent for Northwest Colorado, wants Craig residents to know.

During a trip to Craig this past week, Ekstrom found evidence of the mountain pine beetle and the Ips beetle, also known as the engraver beetle.

Referring to the beetles, Ekstrom said, "There's a severe outbreak in Craig."

And it isn't just Craig. The mountain pine beetle has been identified as far west as Maybell, north as Baggs, Wyo., east as Kansas, and south as Meeker.

There are several varieties of the bark beetle. The mountain pine beetle and Ips are just two of them. Some beetles infect pine trees, while others infect evergreens in general.

"We're dealing with two problems," Ekstrom said. "One is the beetles and the other is blue stain disease."

The reason the two are related is that the mountain pine and other bark beetles have the ability to transmit blue stain fungi. Spores of the fungi are introduced into the tree during attack by the beetles. The fungi grow within the tree and assist the beetles in killing it. The fungi give a blue-gray color to the sapwood.

"Just a few beetles are enough to infest a tree," Ekstrom said. "Only one is needed to spread the deadly blue stain disease.

"Once the mountain pine beetle infests a tree and the blue stain is there, the tree is dead."

The life cycles of various bark beetles are similar to that of the mountain pine beetle. In late summer, the new adult mountain pine beetles leave the dead, yellow to red-needled trees (where they developed) and tunnel under the bark of living green trees.

Each beetle pair mates and produces about 75 eggs that can be found in "egg galleries," or tunnels, under the bark.

The eggs hatch and larvae leave the egg gallery and spend the winter under the bark. The larvae survive by metabolizing a type of alcohol that acts like an anti-freeze.

The larvae transform into pupae in June and July and adults can begin emerging mid-June through September.

Some signs that the mountain pine beetle has infested a tree include the following:

• Popcorn-shaped masses of resin called "pitch tubes" on the trunk where beetle tunneling begins. They may be brown, pink or white.

• Boring dust in bark crevices and on the ground adjacent to the tree base.

• Foliage turning a yellowish to reddish color throughout the entire tree crown.

• Presence of live eggs, larvae, pupae, adults and galleries under the bark - the most certain indication of infestation.

• Blue-stained sapwood.

Ips beetle infestation can be identified by sap pockets or little dots, like tears, on the bark.

Stressed trees - from drought, crowding, old age and other such conditions - are more prone to infestation by bark beetles so it's important to take care of your evergreens.

"The best control is to provide adequate water, fertilizer and a preventative spray program," Ekstrom said.

Providing adequate water, especially in the late fall, is important. Ekstrom advised watering even in December if the ground is open.

Ekstrom recommended using a good garden fertilizer for trees. Sprinkle it on top of the ground and water. Or, even better, using a liquid fertilizer and put it directly into the ground around the trees.

Preventative spraying can be done mid-to-late May until June and has to be done every year. You can spray the trees yourself or have them sprayed. Recommended sprays are formulations of carbaryl (Sevin or others), permethrin (Astro, Dragnet or others) and bifenthrin (Onyx).

Ekstrom said to always read and follow the directions on the spray bottle. He also recommended adding a silicone surfacant to the spray, to help spread the spray and to stick to the tree.

You can get your questions about bark beetles answered at Mountain Pine Beetle Community Meeting, hosted by CSU, at 6 p.m. May 19. The meeting will take place at the Craig Extension Office. Topics covered will include identification, control and management of the beetle.

More on the bark beetles next week.

Copyright Diane Prather, 2008. All rights reserved.

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