Pine bark beetles are relentless predators of pine trees. Although they come in a variety of sizes and colors, and different species infect trees in different areas of the continent, they all have one thing in common: they destroy pines.
Once infected, a tree is doomed and should be cut and removed immediately to prevent other trees from being infected.
Females Lead the Attack
Female pine bark beetles begin attacks. They bore holes into the outer bark of a tree and into the phloem. The phloem is the tissue that carries nutrients to all parts of the tree.
Once inside, the female sends out a pheromone that not only attracts males, but also alerts females, who attack the tree with ferocity.
Mating with the male in the small chamber she has made in the tree, the female will then bore deeper into the tree and lay eggs. In a couple of weeks, the eggs hatch and larvae emerge. They will continue boring through the tree, pupating and then emerging as adults, ready to begin the cycle again.
Beetle-Borne Fungus Also Dangerous
The boring beetles and their offspring aren’t the only things to damage a tree. The beetles carry a blue-green fungus which clogs up the phloem and prevents nutrients from flowing. The combination of the burrowing beetles and the fungi are what deal the death blow to the tree.
Signs of Bark Beetle Infestation
Fading of needles on an entire branch or larger area is a good indication that pine bark beetles are at work. At this point the tree is already beyond help.
Globules of sap or pitch dripping down the trunk are additional indicators. These are a tree’s defense mechanisms, triggered by the boring beetles.
Final indications are sawdust mixed with the pitch, or sawdust around the base of the tree.
Controlling Bark Beetles
Once a bark beetle infestation has begun, there is no way to prevent it from killing the tree, and no chemicals are known to be effective.
Cutting down and removing a tree are the only way to control an infested pine. If not removed, the next generation of beetles hatching and pupating in the old tree will simply move on to newer, uninfected trees.
Prevention
- Thin and remove unhealthy trees, those damaged by lightning, those with other diseases, and trees infested with dwarf mistletoe.
- Water trees during drought if possible.
- Prune healthy trees, removing damaged limbs and branches.
- Do not prune during the periods the insects are actively flying.
- Cut and remove infested trees as soon as they are diagnosed.
Pine Bark Beetle Species
Actually two genus of beetles are lumped into a general category of “pine bark Beetle,” Dendroctonus and Ipps. Both genuses have a number of species that are dangerous to pines. Different species are prevalent in different parts of the country.
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