Between Helena and Butte, Interstate 15 winds and bends like a caffeinated snake, and wise drivers keep their eyes on the road. But I could scarcely keep from staring at the brittle brown forest on either side of the interstate.

I hadn't driven the road in a couple of years, and I was shocked to see the scale of change over that time. Lodgepole pine forests that had been luxuriantly green are now brown and dead. Trees on entire slopes have slipped their needles and stand like stark, naked skeletons.

The trees are being killed by a mountain pine beetle epidemic, a catastrophe cited last week by Gov. Brian Schweitzer and State Forester Bob Harrington, who warned that the vertical kindling could fuel intense wildfires.

The pine beetles themselves seem too small and homely to wreak such calamity. Adult beetles are puny, growing to about 1/8 inch long. Adults are brownish black with a glossy shell. But it's their choice of hosts - almost exclusively mature lodgepole and ponderosa pine stands - and their method of invasion that dooms forests.

Mountain pine beetles are native to the West, but they don't show up in numbers until conditions are right for their propagation. When forest health declines due to drought or overcrowding or fire damage or even old age, the beetles erupt from low background populations to cripple entire forests.

They do it by boring into the bark of mature pine trees. You can tell a pine beetle infestation by popcorn-like masses of pitch on the trunks where the beetles have bored tunnels. Large numbers of woodpeckers hunting these subcutaneous bugs is also a sign of an infestation.

Pine beetle larvae mature under the bark of trees, then emerge in late summer to find new hosts, where they bore into the heartwood and spend the winter. The only sure control of these insects is sustained cold weather, as cold as 30 below for at least five straight days, according to some sources.

If they're not controlled, pine beetles can have a disastrously exponential effect, with each beetle capable of infecting another two to three trees.

So, here's hoping for a wet summer without lightning followed by a brittle-cold, bug-killing winter. That may be the only way we get to see color again between Helena and Butte.

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