SALIDA — The San Isabel and Rio Grande National Forests (USFS) and the Colorado State Forest Service (CSFS) recently observed significant new spruce beetle activity in Chaffee, Custer, Fremont, Huerfano, Las Animas, Pueblo and Saguache Counties. While bark beetles are a natural part of the ecosystem, officials with the U.S. Forest Service Forest Health Protection Unit in Gunnison say the new activity signals an expansion of the ongoing epidemic.
“We expect profound changes to occur in stands of spruce forests due to the actions of these native insects,” said Tom Eager, entomologist with the Forest Health Protection Unit. Already there are significant numbers of dead trees in affected spruce forests.
Public meetings to address spruce beetle concerns will be held in each of the affected counties. A forest entomologist will provide information and answer questions.
The meeting regarding Saguache County’s impact will be held at 7 p.m. Feb. 26 at Salida Scout Hut, Salida.
Spruce beetle activity in Colorado has been on the rise since 2002, with substantial population growth continuing to occur. In a 2012 USFS-CSFS aerial survey, spruce beetle activity was observed on more than 311,000 acres of land in Colorado, with heavy spruce mortality visible in many areas of southern Colorado. This brings the total area impacted by the current spruce beetle infestation in Colorado to almost 1 million acres. Notable affected areas in the state include the La Garita and Weminuche Wilderness Areas on the Rio Grande and San Juan National Forests, and the Greenhorn Peak Wilderness Area of the Wet Mountains on the San Isabel National Forest, as well as many locations outside of Wilderness areas.
The more recently observed spruce beetle activity was not included in the 2012 aerial survey data; however, due to an inability to detect early-stage infestation from an aircraft.
Engelmann spruce, found at elevations between 9,000-12,000 feet, is the primary host for spruce beetles. The beetles typically attack trees that recently were wind thrown. Blue spruce is also somewhat susceptible to spruce beetles, especially in urban communities where Engelmann spruce is not readily available.
When spruce beetle numbers increase, they start attacking standing live trees. However, the spruce beetle discovery in fall 2012 was unusual because the areas of live infested trees are not believed to be associated with a wind event.
Unlike mountain pine beetle, the spruce beetle has a two-year life cycle. Signs of infestation will be noticeable in trees that were wind thrown or newly infested in 2012. Signs of recent infestation include the following:
· On standing trees, reddish-brown boring dust will accumulate at the beetles’ entrance holes, in bark crevices and on the ground around the base of infested trees.
· Masses of pitch, called pitch tubes, will be noticeable around the entrance holes.
· During the first fall and winter following spruce beetle infestations, woodpeckers often will “debark” affected trees. Partially debarked green trees are easy to detect. However, on trees without significant debarking, sawdust in bark crevices and around the base of infested trees is difficult to detect from a distance.
· On wind thrown trees, spruce beetle infestations are readily detected on the undersurface of tree trunks.
During the second year of spruce beetle infestation, needles of affected spruce trees will turn yellowish-green and then fade to grey and drop. (The needles of infested trees do not usually fade or discolor within the first year following infestation).
The CSFS and USFS encourage landowners with forested properties above 9,000 feet in elevation to check their spruce trees now. Private landowners in the affected counties who suspect they have infested trees are encouraged to contact one of the following CSFS office to learn what they can do to treat or mitigate the infestation:
· Saguache County – Adam Moore, 587-0915
Additional Sources of Information:
Rio Grande and San Isabel National Forests:
· Rio Grande National Forest – Mary Nelson, 719-655-2547
· San Isabel National Forest – Alex Rudney, 719-539-3591
· U. S. Forest Service: Forest Insect and Disease Leaflets
· USFS-Region 2: Spruce Beetles
· Colorado State Forest Service: Spruce Beetle