Extension Service Hood River County
Oregon State University, 3005 Experiment Station Drive, Hood River, Oregon 97031
T 541-386-3343| F 541-386-3684 | http://extension.oregonstate.edu/hoodriver/
Outbreak of California Fivespined Ips Bark Beetle
Recent fires and last winter’s ice storms created a great late season smorgasbord of
susceptible pine trees for the California fivespined Ips bark beetle. Top-killed ponderosa
pine trees and dead young and old pines scatter the landscape in the eastern Gorge with
small outbreaks occurring in Mosier, and Hood River Oregon and in Washington around
Underwood, White Salmon and Catherine Creek Trail Area, just west of Lyle. This level of
mortality due to California fivespined Ips has not been previously reported in the eastern
Gorge area.
Entomologists and foresters from the US Forest Service, Oregon Department of Forestry
and Washington Department of Natural Resources and extension specialists from both
states met in early December to tour areas of the eastern Gorge where bark beetle
outbreaks are occurring. The reddening tops of the infested trees became more abundant in
November.
Due to outbreak conditions, experts recommend landowners do pruning and thinning work
before January or wait until mid-October next year. “Normally pruning and thinning work
can be done from July through December but since we are experiencing small outbreaks,
we would suggest landowners prune trees before January or wait until mid-October next
year to do pine tree pruning and thinning work. This is also a good time to remove recently
killed or dying pine trees that show evidence of being infested by bark beetles,” stated Rob
Flowers of Oregon Department of Forestry.
“Tree volatiles from slash piles and fresh pruning wounds seem to be attractive to flying
beetles in the spring and summer months during this period of high beetle populations.
Otherwise healthy trees that should normally resist bark beetle infestations are getting
mass-attacked,” added Glenn Kohler, Entomologist with Washington State Department of
Natural Resources, emphasizing conditions characteristic of outbreaks.
Bark beetles love to take advantage of stressed-out trees. Adult beetles lay eggs underneath
the bark where larvae feed on the living tissue of the bark. High populations can kill both
young and old trees alike. Normally, healthy trees naturally defend themselves from bark
beetle attack by “pitching” them out with sap.
December 2012
The California fivespined Ips was recorded in the Underwood area of Washington State for
the first time in 2010. This species was unknown to occur at damaging population levels in
eastern Oregon until then. The range of this Ips beetle had recently been documented to
extend throughout the Willamette Valley. Now experts have found the beetle as far north
as Fort Lewis, WA in Thurston County and as far east as The Dalles, OR. The California
fivespined Ips only feeds on pine trees and can affect ornamental trees as well as those in
the forest.
“In the previously known ranges of this bark beetle, outbreaks are short-lived, only lasting
for a year or two. If no new fires or storms create slash and stressed trees this next year, I
expect populations to return to normal levels,” stated Todd Murray of WSU Skamania
County Extension.
To avoid beetle populations building up on your healthy pine trees, prune trees only from
mid-October through December during these outbreaks. Right now, weather permitting, is a
great time to work on pruning or removal of infested trees. Clean up all debris and chip or
burn it before next spring when adult beetles emerge. If you have pine trees whose foliage
has rapidly changed to yellow, orange, or red in the past season, it is best to remove these
trees. Beetles within these trees will continue to develop, even if they are felled, unless the
materials are destroyed or de-barked before next spring. Always check with your local fire
district on burning regulations prior to burning debris. If using trees for firewood, be sure to
debark the logs. Promote drying of the logs as soon as possible and do not stack wood near
other pine stands.
To learn more, WSU Extension has developed a factsheet, Pest Watch: California Fivespined
Ips – A pine engraver new to Washington State which can be downloaded for free at:
http://cru.cahe.wsu.edu/CEPublications/FS085E/FS085E.pdf.
For more information, please contact Glenn Ahrens, OSU Extension Forester at 503-6558631 ([email protected]) or Todd Murray ([email protected], 509-427-3931)
at the WSU Extension office. Additional contacts: Rob Flowers ([email protected],
503-945-7396) at Oregon Department of Forestry or Glenn Kohler
([email protected], 360-902-1342) at Washington State Department of Natural
Resources.