Bark Beetle Invasion

"Is that a deciduous tree? Look, I found a little, black insect! Why is that pine tree brown?" These questions and comments have been a common occurrence throughout the school year.  The S.O.S. forest is changing and students are taking notice.  The change has brought up insightful discussions about forest health and management by the students.        

The little black insect stimulating so many questions and concerns is actually native to California.  The Mountain Pine Beetle and the Western Pine Beetle can be found in western North American forests.  Previously, these beetles (no bigger than a cooked piece of rice) caused little harm to the healthy forests of California.  However, California’s years of drought have brought the pine beetle to the front of the stage.  

Figure 1. Mountain Pine Beetle
A student asks, “Ewwww, what’s that red ooze on that tree?”  That red ooze is a sign that the Ponderosa Pine is unsuccessfully trying to fight off the bark beetle.  As previously stated, the bark beetle is native to California but seemingly becomes ‘invasive’ as trees become weakened by drought.  The previous freezing winters of the Sierras use to keep the bark beetle manageable, but warming winters enable the bark beetle to thrive. (1)  The bark beetle attacks the tree by borrowing through the tree’s bark and laying their eggs in the tree’s phloem (Phloem transports nutrients throughout the tree).  The beetle and its larvae survive off of the tree’s nutrients and inhibits the tree to spread valuable nutrients throughout.  The weakened tree can not push the beetle out with its sap and thus becomes a victim.

Figure 2. Aerial View of S.O.S. 2017
Sierra Outdoor School has seen the vast effects from the bark beetle.  Hundreds of ponderosa pines have been cut down since the beginning of the school year. Environmentalists, foresters, and land managers are in a bind of what to do with all the dead trees.  Do we remove the dead trees from the Sierra and initiate environmental damage from logging?  Do we keep the dead trees and increase fire fuel? (1)  The die-off is so catastrophic it is hard to predict what will be best for the environment.        

Although the browning of the trees is aesthetically unappealing, the ponderosa pine die-off has initiated different teaching opportunities and conversation in classes.  The die-off offers hands on ways to approach topics on natural resources, conservation, forest management, and decomposition.   

Figure 3. Aerial Video of Campus 

The forest will adapt to these changes like it has throughout the years.  Sierra Outdoor School will adapt to these changes as well.  On May 6th, S.O.S will be holding a BioBlitz; a public event where volunteers gather to catalog as many species possible to determine the biodiversity of an area.  The goal is to have another BioBlitz in the future to figure out how the biodiversity of the forest is adapting due to the ponderosa pine tree die-off.  

If you would like to attend the S.O.S. BioBlitz you can sign up at: or go to and search for SOS BioBlitz 2017.     



Figure 1.
Figure 2. 
Angel Olavarria
Figure 3. 
Angel Olavarria


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