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Linda Joyce
Rocky Mountain Research Station
240 West Prospect
Fort Collins, CO 80526
Phone: 970-498-2560
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Mountain Pine Beetle  

Solar Treatment Kills Mountain Pine Beetles in Pine Logs

The mountain pine beetle is increasing in ponderosa and lodgepole pine forests throughout much of the West. Decades of fire control have led to overly-dense forests, and now drought has made trees even more susceptible to insect outbreaks. With pesticides in disfavor, solar treatments are an effective alternative to minimize beetle survival and spread in high-value areas such as recreation sites and around homes. Researchers at the Rocky Mountain Research Station found that beetle survival was drastically reduced when attacked trees were felled, cut into 4-foot logs, and exposed to full sun. Rotating the logs once a week so that all surfaces are exposed to the sun, or covering the logs with clear plastic sheeting, increased treatment effectiveness. High temperatures under the bark are key to killing developing beetles before they can emerge and attack healthy trees nearby. Beetle-killed trees should thus be felled in fall or early spring and exposed to hot summer sun to prevent emergence in August. Uncovered logs should not be stacked; even plastic-covered logs should not be stacked more than two high.

Negron, JF, Shepperd, WD, Mata, SA, Popp, JB, Asherin, LA, Schoettle AW. 2001. Solar treatments for reducing survival of mountain pine beetle in infested ponderosa and lodge pole pine logs. Research paper RMRS-RP-30.

Mata S.A., Schmid J.M., Leatherman D.A.. Sept. 2002. Diesel Fuel Oil for increasing Mountain Pine Beetle Mortality in Felled Logs. Rocky Mountain Research Station. USDA Forest Service Research Note RMRS-RN-13, 4pg.



Evidence of Beetle Attacks

Mountain Pine Beetle Brood
(click on images to enlarge)
Adult mountain pine beetle, Dendroctonus ponderosae Hopkins. Black cylindrical, rather stout, beetle about 5mm in length.
Mountain pine beetle brood lying adjacent to a vertical egg gallery. Larvae construct their feeding galleries at right angles to the egg gallery. Larvae, Pupae, and Young adult are seen in their chambers (slide credited to Jose Negron).
Mountain pine beetle egg gallery. Females lay eggs and wedge them on each side of the gallery with packed frass (slide credited to Jose Negron).
The remains of a basal rotted ponderosa pine stump.  Decay can be attributed to fungus and insect damage.

Mountain Pine Beetle (Dendroctonus ponderosae Hopk.) One Year Life Cycle 

The mountain pine beetle has a one year life cycle.  Adult emergence begins about the second week in July and continues on through September, peak emergence occurring mid August.  The brood will over-winter as eggs and young larvae and continue their development in early spring.  Development to adults is completed in mid to late July.

Beetle Emergence

Emergence curves were reconstructed from published Research Notes #32 and #211 authored by W.F. McCambridge, 1964 and J.M. Schmid 1972.  Extracted data from Schmid's report were overlayed for easier viewing.  Actual reports are referenced below. (click on graphs to enlarge).

W.F.McCambridge. 1964. Emergence Period of Black Hills Beetles from Ponderosa Pine in the Central Rocky Mountains. Research Note RM-32, pg.1-4.

Schmid,J.M. 1972. Emergence, attack densities and seasonal trends of Dendroctonus ponderosae in the Black Hills. USDA For. Serv. Res. Note RM-211. 7p.
Identifying Beetle Attacks

Evidence of Beetle attacks
(click on images to enlarge)
Discolored foliage in late Spring is a sign that ponderosa and lodgepole pine trees have been killed by the mountain pine beetle. These trees are called 'faders' and/or 'flag trees' (slide credited to Jose Negron).
Reddish pitchtubes (resin mixed with frass), on the tree trunk and reddish boring dust at the base and also in the bark crevices of the tree, are good indicators of a successful beetle attack (slide credited to Jose Negron).
Unsuccessful beetle attacks are identified by large white pitch tubes on the tree trunk. These resin tubes may have an embedded adult beetle. Coarse frass can be found at the base of the tree. No blue-stain is present and the foliage is green.
Woodpecker damage on beetle infested trees is very noticeable. They make individual holes in the bark as they search for and feed on beetle larvae. Woodpeckers will pick out the best brood producing tree and therefore are good indicators of beetle attacks (slide credited to Jose Negron).
The sapwood of an infested tree will be discolored by a blue staining fungi; the heartwood will not be stained.
Exit and entrance holes are evident on the bark. Entrance holes will be visible during the attack period and exit holes will appear the following emergence period (slide credited to Jose Negron).

William F. McCambridge. 1974. Identifying Ponderosa Pines Infested with Mountain Pine Beetles. Research Note RM-273,pg.1-2.

William F. McCambridge. 1967.Nature of Induced Attacks by the Black Hills Beetle, Dendroctonus ponderosae, (Coleoptera:Scolytidae). Ann. of Entomol. Soc. of Am. 60:920-928.  
Protection Against Beetle Attacks  

(click on images to enlarge)
Solar radiation treatment is an environmentally safe way to kill Mountain pine beetles. Beetle infested trees should be felled in June and bucked into four foot length for easy handling and laid on the ground in an open area where the sun can heat up the bark. Rotate the logs 1/3 of turn, once every week  before beetle emergence begins in late July. Our research results indicated that this method has resulted in better than 95% beetle mortality. Application of diesel fuel oil to infested logs, arranged in a single row, can provide better than 90 percent beetle mortality.
Field tests of insecticides in 1982 determined that spraying green high value trees with 2% emulsion of carbaryl, as Union Carbide Sevimol-4 to thirty feet can protect the tree from beetle attacks (these were the results of research only, and mention of a proprietary product or pesticide does not constitute an endorsement or recommendation by the USDA). New insecticides are now being tested that will produce comparable results at less cost to the consumer.
Even-aged stands with an average diameter greater than 8 inches in growing stock level (GSL) and of more than 120 sq. ft. basal area in Ponderosa pine and 150 sq. ft. basal area in Lodgepole pine stands is considered highly susceptible to mountain pine beetle attacks. Stands thinned to a 100 basal foot per acre or less can increase protection against beetle attacks.

William F. McCambridge. 1982. Field Tests of Insecticides to Protect Ponderosa Pine from the Mountain Pine Beetle(Coleoptera:Scolytidae). J.of Econ. Entomol. 75:1080-1082.

W.F.McCambridge. 1972. Treatment Height for Mountain Pine Beetles in Front Range Ponderosa Pine. Research Note RM-218, pg.1-2.

W.F.McCambridge. 1981. Duration of Effectiveness of Carbaryl in Protecting Ponderosa Pines from Attack by Mountain Pine Beetles. Research Note RM-408, pg.1-3.

W.F.McCambridge and R.E.Stevens. 1982. Effectiveness of Thinning Ponderosa Pine Stands in Reducing Mountain Pine Beetle-Caused Tree Losses in the Black Hills--Preliminary Observations.  Research Note RM-414, pg.1-3.

Robert E. Stevens, William F. McCambridge, and Carleton B. Edminster. 1980. Risk Rating Guide for Mountain Pine Beetle in Black Hills Ponderosa Pine.  Research Note RM-385, pg.1-2.  

William F. McCambridge, Frank G. Hawksworth, Carleton B. Edminster and John G. Laut. 1982. Ponderosa Pine Mortality Resulting from a Mountain Pine Beetle Outbreak. Research Note RM-235, pg.1-7.

Ponderosa Pine Cones and Associated Insects

Schmid, J.M., Mata, S.A., and Mitchell, J.C.  1985.  Estimating Sound Seeds in Ponderosa Pine Cones from Half-Face Counts.  Research Note RM-459, pg. 1-3.

Schmid, J.M., Mata, S.A., and Mitchell, J.C.  1986.  Number and Condition of Seeds in Ponderosa Pine Cones in Central Arizona.  Great Basin Naturalist, Vol. 46, pg. 449-451.

Schmid, J.M., Mitchell, J.C., and Mata, S.A.  1986.  Ponderosa Pine Conelet and Cone Mortality in Central Arizona.  Great Basin Naturalist, Vol. 46, pg. 445-448.


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