Following the Tracks of a Killer Mountain Beetle
by: Charles Petit 31 January 2007
In early September, Jesse Logan, a 62-year-old insect specialist with a knack for mathematics and a deep love for the Western landscape, gazed across a rolling meadow 10,400 feet high in the rugged Wind River Range in Wyoming.
Moving carefully with the aid of two trekking poles, Dr. Logan favored a left knee injured three years ago by a Colorado avalanche that killed a close friend. He had not been sure he would ever get into back country like this again. Yet here he was, nearing the end of an arduous expedition, organized and led by Louisa Willcox, director of the wild bears project for the National Resources Defense Council, carrying a 40-pound pack over 12,000-foot passes in a roadless wilderness.
Dr. Logan is an authority on the effects of temperature on insect life cycles. Across the way he could see likely signs of a particularly aggressive organism he was seeking but hoping not to find here, the mountain pine beetle.
The beetle is the most destructive timber pest in the Western United States. The rising warmth across the Rockies is expanding its range north and, equally important, uphill. Dr. Logan had hoped to find no incipient, major outbreaks here. But many of the pine trees across the way were an unhealthy red. This did not look good.
"We'd better go look," he said. He walked through brush littered with elk droppings with two friends and research colleagues, Jacques Régnière of the Canadian Forest Service and Wally MacFarlane, an experienced mapmaker and geographic analyst from Logan, Utah.
They were on the flank of Tybo Peak. Each had a permit from the Wind River Reservation tribal government to be in this seldom-visited corner of Indian Country, which may be among the most remote wildernesses in the lower 48 states. They scrambled uphill into a nearly pure stand of high-altitude, whitebark pines.
Dr. Logan regards the high, whitebark ecosystem as "the most beautiful in all the Rockies," yet the public hardly even is aware of its existence. For most of the trip he had looked out on gloriously healthy forests of these trees, but not now. Some here were bright, brick red. The men took out small hatchets.
Looking closely, the party could see perfectly round holes speckling the bark, each about the size of a BB. Some infested trees were oozing dark pitch from the holes. Dr. Logan whacked a 40-foot-tall tree with his hatchet. He peeled off a piece of bark about eight inches across.
The air filled with a rich, piney aroma.
In the pale, exposed tissue, white beetle larvae glistened. Dr. Logan looked up at the foliage, still more green than not. "This tree is dead," he said. "It just doesn't know it yet."
He pointed out characteristic J-shaped, largely vertical tracks chewed in the inner bark, or phloem, by the insects. Several of the black, blunt adults, each about a quarter-inch long, moved slowly.
Light blue splotches of fuzzy fungus were taking hold, spreading from spores the beetles carry in their mouth parts. The fungus, along with the beetle tunnels, blocks movement of sap. "These are true predators," Dr. Logan said. "They have to kill to reproduce. Most other bark beetles don't do that."
As the party worked its way through the yellowing and red trees, something was peculiar. It was late summer, yet in some trees the female beetles were just boring in. In other whitebarks a short distance away, Dr. Régnière found a different state of affairs. Some bore only larvae. In others were newly molted beetles at the so-called teneral adult stage: pale brown and lacking the dark, hard carapace of an insect ready to fly.
With cold weather only weeks away, this generation of beetle did not have time to get a new larval generation started before winter set in. Out of rhythm with one another and the seasons, these beetles looked unlikely to muster the type of mass attack that can turn a forest of mature pines into deadwood in a few seasons. Scattered about were snags and fallen trees, many bearing beetle tunnel gallery scars.
The insects have been puttering in this south-facing, sunny grove for a long time without catching their full stride. A similar grove nearby told the same story. A few days earlier and miles to the north the team had found a smaller, sun-favored stretch with signs of low-level beetle activity that appeared to have been eking along for centuries.
"I think we're O.K. here," Dr. Logan said.