In the insect world, communication within a species can be through several media. They can communicate through sight and movement, such as the honeybee "waggle dance". They can communicate through sound like the chirping of cicadas. By far the biggest is the media of smell. Pheromones are chemicals produced by insects and animals and even some plants that affect behavior. Sometimes the behavior of another member of your species, sometimes a member of a totally different species (Truffles, for example, produce a pheromone similar to a sexual attractant pheromone produced by mammalian males. That's why pigs can "smell" them and find them) Some have an odor to them, some do not.

The bark beetle's pheromone lexicon is pretty ingenious. When an adult male locates a susceptible tree (remember from Act II-A how they can hear stress), they land on the bark and chew into the inner bark. If they're successful and haven't been drowned by the tree's pitch, they emit a pheromone that attracts other bark beetles, male and female. "Hey. I found a way into the store! There's lots of loot!"

At some point, after a number of other beetles have taken the invitation (particularly the females), now the original colonizers start issuing a pheromone that says, "Buzz off. No room at the trough!" Kind of the chemical equivalent of gang tagging their territory.

Mountain pine beetle galleryMountain pine beetle galleryThe beetles do damage in two ways. First, the adults that make it past the outer bark, begin to feed on the inner bark. The inner bark contains the phloem, the food carrying part of the tree. The female also lays eggs here and when they hatch, the larvae also begins to chew tunnels through the phloem. Its effect is to girdle or sever the highway between the food producing needles and the food needy roots. Roots that can't get food will die and now they can't pump up water and minerals to the needles above. Not good at all for the tree, but the tree still have a shot at surviving.

The second type of damage, the double whammy for the tree, is the fungus that the beetles carry on their body. This fungus, called blue stain fungus, infects the sapwood of the tree. The sapwood is the newest wood of a tree, from the last 3 to 10 annual rings of growth. The sapwood contains the xylem, the water and mineral conducting vessels. The fungus grows rapidly and clogs this xylem up. That means sudden death to the tree. No water, no leaves or needles.

Blue stain fungus got its name because it stains the wood blue. When beetle killed trees go to a sawmill Blue stain fungusBlue stain funguswhat gets milled out are boards with a bluish cast to them. When I was an extension agent in Colorado, a couple decades ago, blue stained lumber was just coming down from a peak demand craze. For awhile, everybody wanted to line their rec rooms with blue stain board paneling. With lots of beetle killed trees and lots of demand, local loggers were doing well. No fads last forever, and soon blue stain lumber was old hat. Instead of beetle killed stands being harvested, they were left standing and the incidences and severity of forest fires went up.

We have now large areas of dead standing timber thanks to the bark beetles. Every year we seem to have a fire season worse than the preceding year. What is causing this escalating plague of bark beetles? How can we stem the tide? That will be Bark Beetle Boy: Act III - The Dramatic Conclusion.

(Note to Marvel: So of course, we'll have the Army, Air Force, Seals and Marines all battling Bark Beetle Boy and the Legion, but to no avail.

Scene: (Field Commander in tent. Military personnel racing around.)
Commander: "Nothing we do seems to work! Every stratagem, every maneuver we make they anticipate! It's as if they read our minds."

(From the dark background of the tent, an old bearded guy in suspenders shuffles up.)

Old Bearded Guy: "Nah, chief, they're not reading your mind, they're smelling it. If you want a chance, you gotta fight smell with smell. Here." (Hands an aerosol can to the Commander)

Commander: "What's this? Date-Mate??"

Old Bearded Guy: " It's a sexual attractant pheromone. Spray this on every tank, plane and soldier we have. Not only will they know we're coming, but they'll come to us. Love will conquer all."

F & P