The persistent little bugs that have turned countless acres of Montana forestland from deep greens to dry reds and browns have begun attacking trees on Mount Helena.

Patches of dead ponderosa pine now dot the east and west flanks of the limestone-crowned city park and soon more trees will be killed by the relentless attack of the western and mountain pine beetles' hungry offspring.

"It's just mild, it's just starting," said Jim Cancroft, a private forester. "But it has the potential to be big because of stand conditions and the way things are going."

City officials and the Helena Open Lands Management Advisory Committee, or HOLMAC, have begun mapping out their counterattack.

The city will use grant money to thin some stands, with the dual goal of reducing fire fuels and opening up the canopy - decreasing the bugs' shelter from the sun and wind.

Officials also plan to battle the beetles this spring with pheromone traps and repellants.

Cancroft, a HOLMAC member, said he's also observed signs of the attack scattered throughout the city's 2,000 acres of open land, including the slopes of Mount Ascension.

The beetles, along with the western spruce budworm, are native in the Montana landscape, but years of dry summers and mild winters - following decades of fire suppression, which has increased woodland densities - have weakened trees and allowed the bugs to go into overdrive.

"It's a natural part of the ecosystem, but it's an epidemic in this area now," Cancroft said.

Helena National Forest officials estimate the critters have affected about 100,000 acres, or one-tenth of the forest.

Helena Parks and Recreation Director Randy Lilje said the city has received a $55,000 federal grant for fuel reduction, which it will match with funds from the new open space maintenance fee. The thinning work is set for about 100 acres on the west side of Mount Helena City Park.

The city's also applied for Federal Emergency Management Agency funds for thinning work on the east side of the mountain and at other sites throughout Helena's publicly owned open lands.

Cancroft said the city and HOLMAC will ask county officials for about $20,000 in locally distributed federal funds to do additional thinning and purchase pheromones.

Beetles prefer stands with higher densities to protect them from the sun and wind, Cancroft said, so thinning the canopy makes the area less attractive to the bugs.

When they land on a new tree, the beetles emit pheromones, or reproductive attractants, to draw others to the plant.

Cancroft said HOLMAC and city officials plan to use two types of pheromones in the spring. One lures the bugs into traps. The other is a repellent, hung in canisters high in the trees. It tricks beetles by emitting a signal telling them the tree is full of bugs and can't house more.

He said officials will try both types and see what works.

The least attractive option is pesticides. The chemicals are costly, deadly to other insects and unpopular with the public, Cancroft and Lilje said.

Deadly borers

In recent weeks, western and mountain pine beetles have left the trees in which they've spent their whole lives and sought new hosts. In a mass attack, they are now boring into the trees to lay eggs. Next year, larvae will feed on the cambium, which is responsible for the trees' tissue and bark growth.

Healthy trees have mechanisms to repel the bugs, but sustained drought has weakened the plants near here, and recent mild winters have allowed beetles' numbers to grow.

Trees may use sap or pitch to try to shoot the bugs back out, forester Jim Cancroft said. Weak trees cannot produce enough pitch to fend off the beetles.

The red and brown trees appearing in nearby open lands were attacked two years ago, he said, with larvae hatching last year.