CANYON CITY – As if fire, drought and weeds weren’t enough, damaging insect populations are on the rise in forests of Grant County.

According to Mitch Mund, stewardship forester, bark beetles and tree-damaging insect populations “go in cycles” – and the current trend is producing increasing damage across Eastern Oregon.

Mund and Kirk Ausland, stewardship foresters with the state Department of Forestry, visited the Grant County Court last week, bringing along maps showing insect data on forests within the county.

The maps were created with data taken from fly-overs across the state in 2007. The ODF, working with the Forest Service, conducts the surveys in the summer and fall months, using an aircraft that flies 1,000 to 1,500 above the ground over a grid pattern. Observers record the damage, charting the terrain, tree species and affected areas.

According to an accompanying report from ODF, the effort detected a substantial increase in damage from 2006 to 2007.

“In 2007, detected damage to forestlands in Eastern Oregon increased by 40 percent overall, with the majority of the damage occurring on national forest and designated wilderness areas,” the report stated.

The increase looked worrisome to county officials. Commissioner Boyd Britton asked what could be done about it.

“The most important thing you can do is have a healthy forest,” Mund said.

Unfortunately, the forest ecosystem is already impaired by human actions in the past, drought conditions, stand age, crowding of trees and competition for nutrients, Mund said. Those factors combine to stress the trees and make them more vulnerable to insect infestations, he said.

The biggest culprits shown by the mapping are bark beetles and defoliators – insects that eat the foliage of trees – such as western spruce budworm and larch casebearer.

The ODF maps show the greatest spruce budworm damage occurring near Logan Valley, in southern Grant County. Spruce budworms, which feed on the needles of conifers, are affecting large tracts around Logan Valley. Damage from the larch casebearer, which can stunt the growth of larch tree species, is more common in the northeastern portion of the county. The study also noted that ground surveys have found high levels of needle cast and blight affecting Western larch in the region.

Mund said insect populations can boom in relatively short span of time.

He described observing a stand of trees on the Umatilla National Forest five or six years ago that had a half-acre patch affected by spruce budworm.

“It took off and just exploded over the next couple of years,” he recalled.

The damaged area expanded as the voracious insects ate not just the needles of the host plants – true firs are preferred – but other greenery, even thistles.

“Anything that was green, they were eating it,” he said.

The ODF study notes that in Eastern Oregon, the damage from defoliators is up by an average of 70 percent.

The aerial survey captures a snapshot of activity for a particular year, and may not be indicative of a larger trend, the report notes.

“Still aerial surveys represent the best method available for obtaining reasonable depictions of the extent of forestlands affected by damaging agents, and serve to continually update managers as to changing conditions in these areas,” the report states.

Mund said the last large spruce budworm outbreak was about 25-30 years ago.

Back then, Forest Service managers were able to use Bt (bacillus thuringiensis) a bacterial control, to try to curb some outbreaks, Mund said. He and Ausland said they doubted that could be done now on federal lands, but foresters could take other steps to strengthen forest health.

They suggested that logging, thinning and clean-up efforts could “mimic the natural processes” to try to bring forests back to a more resilient state.

The County Court offered to refer the survey maps and report to the next meeting of the Blue Mountains Forest Partners, a collaborative group that is drafting plans for stewardship projects on the Malheur National Forest.