Craig Results of the 2007 annual forest health aerial survey, completed by the Colorado State Forest Service and U.S. Forest Service, reveal that the bark beetle affected about half a million new Colorado forest acres in 2007.
That brings the total number of acres of infestation up to 1 million since the first signs of outbreak in 1996.
According to the survey results, announced Jan. 17, 2008, most of the lodgepole forests in Colorado have some level of tree mortality caused by the mountain pine beetle. The majority of large lodgepole pine has been killed.
The mountain pine beetle has run its course in some lodgepole pine forests. Places such as the Williams Fork and the Troublesome areas in Grand County won't show any new activity.
In other areas across Colorado, generally north of Leadville, the epidemic in lodgepole pine has expanded and intensified. The mountain pine beetle reached epidemic levels in high elevation lodgepole pine forests in Boulder, Chaffee, Clear Creek, Gilpin, Lake and Larimer counties. For example, Boulder and Larimer counties have seen more than a 1,500 percent increase in beetle activity in the past year.
Bill Ekstrom, CSU Extension Agent for Northwest Colorado, said Moffat County is not represented in the aerial survey because there are no forests in the county.
"Dead and dying trees that were isolated to five northern Colorado counties last year can now be seen in some Front Range areas, as well as southern Wyoming," said Rick Cables, Rocky Mountain Regional Forester for the U.S. Forest Service. "Working with our many partners to mitigate impacts to high-value areas from the bark beetle epidemic is top priority for the Forest Service."
Jeff Jahnke, the director of the Colorado State Forest Service at Colorado State University, said "Restoring forest health and reducing fire danger across such an expansive area requires an investment in human and financial capital on the part of all stakeholders, including land management agencies, local communities, private landholders, environmental organizations, and elected officials in order to be successful."
The mountain pine beetle, once known as the Black Hills beetle or Rocky Mountain beetle, is a natural part of the lodgepole pine ecosystems, but the recent warm winters and drought conditions have resulted in favorable environmental conditions for the beetle to spread.
The mountain pine beetle develops in pines, especially lodgepole, ponderosa, Scotch, and limber pine.
Bark beetle relatives of the mountain pine beetle (in the same genus) also affect forest trees. The Ips beetle, mentioned in last week's story about bark beetles, is of another genus.
According to CSU Bulletin, Number 5.528, "Mountain Pine Beetle," natural controls of the bark beetle include woodpeckers and clerid beetles that feed on adults and larvae that are under the bark. However, during outbreaks, these natural controls often fail to prevent additional beetle attacks.
Another natural control is freezing temperatures. However, for this control to affect large numbers of beetles, the freezing temperatures have to come at precise times of insect development. For example, the cold weather has to come before the larvae start metabolizing the glycerol (which acts like antifreeze during the winter). The temperature must be at least 30 degrees below zero and last for at least five days.
If there is a severe freeze in late spring when the pupae are forming, it may kill this stage of insect development. To find out more about the bark beetle in our area, you can attend a community meeting about the mountain pine beetle at 6:00 p.m. May 19 at the Craig Extension Office.
Your questions also can be directed to Bill Ekstrom at 878-9490.