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August 22, 2016
Vol. 3, Issue 4
August 2016
Save the Date!     
August 25-26
- California Society of American Foresters 2016 Summer Meeting: A Centennial Celebration - Professional Forestry in California; Chukchansi Gold Resort, Coarsegold, CA

September 13-15 -
Coast Redwood Forest Symposium: Past Successes and Future Directions; Sequoia Conference Center, Eureka, CA

November 15-16 - California Forest Pest Council Annual Meeting; UC Davis Student Community Center, Davis, CA
Know Your Pest - Western Pine Beetle
The western pine beetle (WPB, Dendroctonus brevicomis) occurs throughout much of the
Western Pine Beetle Galleries.
By Chris Lee, Cal Fire.
West, but it is particularly destructive in California, where it aggressively kills ponderosa and Coulter pines. Normally this beetle kills overmature, windthrown, or root-rotted trees, but during severe drought episodes, population levels can explode, leading to epidemics in which large groups of seemingly healthy trees are killed.
The WPB usually kills trees over 6" in diameter, as smaller trees have bark that is too thin to protect
Western Pine Beetle Larva. By Chris Lee, Cal Fire. 
young beetles during development. Each WPB attack involves a female and male. A stressed tree may experience thousands of attacks. The adult beetles often transport stain-causing fungi with them, which grow within the tree's vascular system and hasten tree death. After they enter the bark, adult beetles construct winding, spaghetti-like galleries and lay eggs within them. The larvae hatch, consume tree tissues, and gradually move toward the outer bark as they prepare to pupate and exit as adults. In the northern part of their range and at higher elevations, WPB can produce 2 generations a year; in the southern part of their range and at lower elevations,
Western Pine Beetle in Pitch Tube. By Chris Lee, Cal Fire. 
3-4 generations can be produced.
Signs of WPB attack include mid-trunk whitish to pinkish pitch tubes that gradually expand toward the bottom and top of the tree, boring dust on the outside of the tree, and removal of patches of outer bark by woodpeckers. Once beetles enter the tree en masse, nothing can be done to save it. Prevention of WPB attacks depends on alleviation of tree stress by thinning dense stands during non-drought years and deep watering of individual trees beginning in spring during drought years. Preventative use of contact insecticides and pheromones may also be successful for some trees.
For more information on WPB, go to . For more information on managing bark beetles, go to . 
Snapshot of Western Pine Beetle Activity in California
Western pine beetle (WPB)-caused tree mortality in 2015 impacted approximately 635,000 acres statewide, a twofold increase from 2014. Ten Sierra Nevada counties have had dramatic landscape-level ponderosa and Coulter pine tree mortality, while
Western Pine Beetle Impacts.
By Henry Herrera, Cal Fire.
counties in southern California have had localized dieoff.
In southern San Benito County, Coulter pine mortality levels increased dramatically in several locations. Dieoff of ponderosa pine was severe in Sequoia National Forest as well as the Los Padres National Forest through the Tehachapi Range and into the southern Sierra Nevada Range. Intense Coulter pine mortality occurred in portions of Santa Barbara County, and in San Bernardino County there were severe patches of ponderosa and Coulter pine dieoff. Although impacts in the northern half of the state were not as predominant at the landscape level in 2015, WPB-caused ponderosa pine mortality did increase greatly in many areas, including the northeastern corner of the state (Tahoe, Plumas, Lassen, and Modoc National Forests), Boggs Mountain Demonstration State Forest (Lake County), and the Klamath Mountains region of Trinity and Shasta Counties. Impacts from WPB in 2016 await US Forest Service aerial survey findings, but are expected to be even more considerable than 2015 across the state. 
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When buying firewood for home heating or camping, remember to buy it from local sources, helping to minimize the spread of pests and diseases - Buy It Where You Burn It.  For a list of firewood dealers local to where you live, go to


Katie Harrell
Communications Director  
California Forest Pest Council
California Forest Pest Council | (510) 847-5482 | |

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