Mountain Pine Beetle

As Wyoming cruises to the End of the 2010 Mountain Pine Beetle Season, let's explore this little devastator of the forest's Rise to Fame. The Mountain Pine Beetle (MPB) has existed in the Ecosystem for Thousands of years. Normally there would have only been small localized pockets from one forest to the next. But here in the United States the USFS began a campaign to eliminate fire from the ecosystem by creating the Smokey the Bear, "Only YOU can prevent forest Fires!" campaign. This was the infancy of this current outbreak's legacy.

Historically, forest fires burned small patches, mosaics you could call them, of trees under very strict environmental circumstances. From the air one would have seen what appeared like a jig saw puzzle with each piece of the puzzle being a different stand of trees, maybe hundreds of acres each but of different age classes. Today, one might see these mosaics in the Pacific Northwest, produced by "Clear Cutting", a reproduction method to mimic a forest fire. But of course the Spotted Owl scam shut down our logging industry and sent thousands to the bread line, but that's a discussion for another day.

Forest fires have an affinity for old growth forest and dog hair stands of trees, especially during drought or insect outbreaks. From 1900 and earlier, forest fires would burn a patch here or there but then when it ran up to an area where another fire had burned within the last 20 years, the fire would stop because there were no more fuels to carry the fire. These stand replacing fires (Crown Fires) normally occur in closed canopy stands (about 50 years+) with enough accumulated fuels on the surface to get the fire started and from there "Crown Out".

Health improving forest fires were those that burned along the ground in stands that were more open in nature and where a ground fire just can't jump into a tree. These fires occur every 10 - 15 years clearing the surface of any accumulated "ladder fuels". Also the special distribution of the individual trees was at a distance that was just too far a tree that might "flame" to jump to another tree. These fires burned slowly along the surface, some of them for months. Another factor has to do with the moisture content of the stand of trees in the fires path. Fuels are dead trees as a result of disease or insect outbreaks, needles or over grown shrubs or grasses. Ladder fuels are small trees or shrubs whose tops reach up into the bottom portion of a larger trees canopy. When the Hot Shots, Smoke Jumpers and Air tankers started putting out every fire that came along, the forest wasn't replaced or thinned out but rather continued to age, but more importantly, the natural fire breaks created from fires in the past, no longer remain. From the air, everything looks the same now, not many jig saw puzzle pieces left down there! That, my friends is what created the present situation our forests find themselves in today. A continuous stand of trees from New Mexico to Canada all over 50 years old (more like 140 years), fuels from the old needles that are cast off every year, dead trees half fallen over acting as ladder fuels and overgrown shrubs, dead, due to drought and ready to become a King Kong sized Bic lighter. There, I said it!!

Pine trees have a natural defense against this beetle; they "pitch" them out. When a beetle burrows into the tree trunk sap begins to flow very quickly from the hole. The beetle at this point really needs to more resemble a fish than an insect because it is an upstream swim to the prize. The sap merely flows out the tiny hole made by the beetle, taking the beetle with it, outside the tree's bark where it dies from exposure (stuck in the sap) or a bird eats it. There's only one flaw with this defense system, it takes snow and rain to produce these sap flows. When trees experience years of low precipitation, as is the case during a drought, the sap flow slows down. Every year the flow is less than the year before as long as precipitation decreases, until the beetle can swim upstream and breach the trees defense mechanisms. Then and only then can the party begin. Scout beetles find susceptible host trees and once in "ring" a dinner bell called an "Aggregation Pheromone". All beetle with a nose, fly into the wind until they too find the unlucky victim that they then Mass Attack. As the beetles dig into the cambium layer or that layer responsible for carrying the "sap" they also transmit a disease that is carried on the attacking beetle body. This disease is named "Blue Stain" because the disease stains the wood from grey to a nice blue color. This fungus stops water from moving in the tree and that in itself is another contributing factor to the death of the tree the following year during July or August. Trees can be sprayed with a chemical that can kill or repel the beetles from the selected tree.

The most critical factor is that the spraying company makes a proper application, spraying the tree 40' up the trunk and spraying from three sides. No exceptions! "Anti Aggregation Pheromones" can be applied to individual trees that act as a "NO Vacancy" sign causing the beetles to bypass this particular tree and find a different one. If the beetle can't find a tree and I assume they then get all stressed out, they may try to attack a young healthier tree only to be pitched out. Trees that were mass attacked this season are the only trees that pose a threat to the adjacent trees next season. These trees should be removed any time after Thanksgiving when it's safe to assume the flight is over. I prefer logging during the winter when snow covers the ground and skidders can travel across the surface without disturbing the understory vegetation. If you log beetle infested trees in June, July or August, you just may attract them to your location, that pine smell in the air when bucking up firewood seems to act like a dinner bell as reported by some landowners in the area. You may inadvertently encourage the attack of trees in your proximity.

I hope this sheds light on this insect and some history leading up to its Star Power and current Rise to Fame.

Todd