Spruce Beetles Enjoying Summer in the Mountains
Forest rangers were on hand this week to educate the public about the next wave of bug infestations in southwester Colorado: the spruce beetle. As its name suggests, this little black to reddish brown bug goes after only the spruce tree. The beetle is hardy, surviving most winters by burrowing underneath bark. And with the drought, it has proliferated in this thickly forested area.
Mountain trees have insect invaders for every variety. Pines and fir are suspectible to beetles as well. A disease called armillaria goes after tree roots, and the spruce has another enemy: the bud worm.
But this year forest officials are taking a proactive approach by thinning forest areas where stands of diseased and weakened trees are located. By felling trees that are diseased, the beetle has less opportunity to jump onto the next nearby tree. Thinning out also helps trees steer clear of migrating beetles.
Healthy trees can sometimes repel bugs by producing sap that creates a barrier the bug cannot get across.
Gretchen Fitzgerald, a San Juan National Forest reforestation specialist, noted that besides sap, other conditions can discourage the bugs.
Because beetles send out pheromones that attract even more beetles, she explained, it is possible to disrupt the cycle with a winter cold enough to wipe out beetles living under the bark of their tree hosts, or by a particularly wet summer.