The Forester and Beetles
As the Forester at the homestead showed me his thinned Doug Fir stand (thinned to 15-feet between trees and planted with native grass for ungulate grazing), I heard an alarm clock ticking in a pile of wood.
Contrast the photo above with the one taken at the ski hill below. The Forester has removed all the dead and down trees from his stand to fight the threat of both a super-hot forest fire and beetles. The ski hill has not.
He said the alarm clock I heard was Flathead Wood Borer Beetles.
Two-inch-long metallic beetles that lay eggs under bark.
The eggs develop into larvae that overwinter under the bark.
Adults emerge in the spring and look for new trees.
Not only do they bore into heart wood, they also introduce yeast, bacteria, and fungi that hasten the death of the tree.
Flathead Wood Borer beetles chomping from inside the wood make the wood sound like it's ticking.
Before fire-suppression and climate change, tree beetles served an important purpose: they got rid of old and diseased trees and helped keep the forest young and flourishing.
Spruce Beetles
Beetles harming forests in Montana:
- Western Spruce Beetle
- Doug Fir Beetle
- Mountain Pine Beetle (which attacks Lodgepole, Ponderosa, Whitebark, Limber, Scotch and Jack Pines)
They have similar life histories to Flathead Wood Borer Beetles.
They overwinter under the bark of their preferred tree species.
Adults bore out of infected trees in the spring and "fly" to uninfected trees.
With shorter, warmer winters, there are more beetles than ever.
The Forester says that tree beetles launch from the upper branches of mature trees, float down, land on and infect younger trees. If trees are thinned, the beetle may land on the ground and die.
Mountain Pine Beetle has caused the largest forest blight ever seen in North America. It is currently devastating forests in all western states and Canadian provinces.
Healthy Limber Pine - they occur at high elevation and even old trees can appear shrub-like.
Spruce Beetles have killed millions of trees everywhere there are spruce forests - especially Alaska where 2,000,000 acres of Englemann Spruce forests have been destroyed.
Spruce Cones
Doug Fir Beetles have done similar damage.
Old Doug Fir Stand - these trees are probably 500 years old. See how widely spaced they are. Low-temperature, naturally-occurring forest fires kept this stand healthy by burning dead and downed trees for hundreds of years before modern fire-suppression. So far, beetles have not infected this stand.
Healthy trees have natural defense systems against beetles that work great under normal conditions. But trees can become overwhelmed by:
Large Number of Beetles
Drought
Defoliation
Pollution
Fire-suppression
Logging and Monocultural Replanting
Climate change
Disease
The loss of these millions of trees has lessened the ability of forests to remove CO2 from the atmosphere.
Foresters use packets of pheromones nailed to the tree to chemically tell adult beetles, "Move along, this tree is taken."
Pheromones can also drive beetles out of an already infected tree. The Forester then sets cone traps for the beetles. They fall in, die, and then a bear digs them up and has a beetle cone.
The homestead had five inches of snow the first week in June and the Forester lost some young trees.
Snow load on young trees is another stressor that can make them susceptible to beetles.
He’s tied up the ones he can save. See the yellow line below.
Wasps, flies, and other beetles prey on the tree beetle larvae and are important in controlling outbreaks.
Another tree beetle predator - woodpeckers!
Williamson's Sapsucker
Get those beetles!