Responsible Earth

Bark Beetles

Bark, spruce, and pinyon ips                     beetles--Utah's three prevalent beetle     species--have coevolved with their         host trees over thousands of years;         therefore, beetle attacks are a natural     disturbance in forests. Beetles are             small (size of a grain of rice) and               typically target fallen trees or those             weakened by disease and drought.         Beetle infestations, though unsightly,         "weeds" out genetically inferior trees         thus facilitating the growth of an                 ultimately healthier forest.

So...what's the issue?

Recent record-breaking temperatures in Utah allow for bark beetles to complete two     life cycles (bivoltine) versus the historical one (univoltine). Ultimately, this means           that twice as many beetles are present in a single season.

Beetles target drought-stressed trees, which is pretty much most trees in Utah due         to higher temperatures and less snowfall. More beetles are infesting more trees.
    Beetle attacks cause infested trees to undergo five phases over about a decade:             green (<1 year post infestation), red (1-4 years), grey (4+ years), tree fall (4-10+         years), and the forest regeneration phase (10+ years). As a result, for roughly 10     years, the trees turn red, drop their needles, and fall--not quite the ideal situation for     local ski resorts who rely on healthy forests to bring business.


    While beetle-infestations are part of a healthy forest's life cycle, those whose                 livelihoods depend on healthy forests are not so willing to let their evergreens go             without a fight.

Ross Chambless' article "Alta Fights to Stop Bark Beetles" showcases how the             resort is actively protecting their oldest pines; small pouches of an                                    anti-aggregant pheromone, verbenone, are stapled to the trunk. Ski resorts exist         because of mature trees holding together steep slopes and preventing                     avalanches. It is crucial to preserve the 50-100 year old stands of Little Cottonwood;     Responsible Earth is always seeking partnerships with local businesses with native         preservation, such as Alta ski resort.


What is our responsibility?

That is the question, is it not? What can we do about a natural, albeit magnified,             disturbance that will ultimately pave the way for a healthier forest? Unfortunately, we     humans are the only ones who think infestations are an "issue." Beetle-killed                 forests will regenerate and will be infested again. The cycle will proceed whether we     like it or not. So, what can you do?

    The first signs of a beetle infestation are reddish-
    brown boring dust
(frass) around entrance holes         and the base of the tree. Pine beetles tend to                 attack the middle of the trunk first and spruce             beetles can attack one side of the trunk, known as       a "strip attack."

    Woodpeckers debark infested trees to access the             beetles (as shown in the figure to the right). Debarking     is easily noticeable, but trees that have not been                 debarked require more careful observation to identify         an infestation.

   Red needles on trees are an obvious sign of infestation, 

    but do not occur until around a year following the initial attack.

    Recognizing signs of a beetle attack early can allow for the implication of                        preventative measures before a massive infestation. Contact your local USDA            Forest Service with information on new attacks.

    For more information on Utah's bark beetles, visit:
       Forest Service - Bark Beetle
       Forest Service - Spruce Beetle

For more information on the numerous ecological effects of beetle infestations, Eric       Gordon and Evan Pugh have an excellent presentation here:
       A Conceptual Model of Water-Related Impacts from Bark Beetle Infestations