Mountain Pine Beetle

          Affecting Scotch pine, ponderosa pine, limber pine, and spruce in some cases.

Summary Management Statement
Ten Points on Management
Detailed Information

Slide Presentation of Mountain Pine Beetle and Spruce Ips Beetle Management
                                                            
                                                                    All Photos: Cheyenne Urban Forestry

  
Popcorn like globs of sap or pitch oozing out of entrance holes made by Mountain Pine Beetle (MPB) in
           Scotch Pine.  MPB came into Cheyenne inside infested firewood and possibly riding in upper air currents.    

   
Ponderosa pine showing numerous "hits" by MPB, with sap or pitch oozing out. Not all attacked trees will show pitch or sap around the entrance hole. Sometimes the most visible evidence of MPB attack will be boring dust (looks like saw dust) at the base of trees.  MPB came into Cheyenne inside infested firewood and possibly riding in upper air currents.

                    
      Sap oozing out of entrance holes made by MPB.  Open holes in the trunk and wood boring dust mixed                                                                      with sap may indicate a successful attack.


                    
    Mountain Pine Beetle constructing the new home. MPB came into Cheyenne inside infested firewood                                                               and possibly riding in upper air currents.
   

                                            
                            Woodpecker activity in a tree is a good indicator of the presence of bark beetles.

                                           
                                Even the bugs have bugs. Mites on the back of a Mountain Pine Beetle.

Summary:

All pine tree trunks larger than 4 inches in diameter should be sprayed with an insecticide labeled for Mountain Pine Beetle (MPB) before mid-June. Any pine tree already successfully attacked by MPB should be removed before June. Properly dispose of infested wood at the Cheyenne Compost Facility - 3714 Windmill Road.

Ten Points about Mountain Pine Beetle Management:

1. Keep your pines healthy. Water trees year-round. Do not cut the tree roots. Reduce or eliminate the use of weed killers near the tree. Do not compact the soil around the tree. Mulch the soil under the drip line with coarse organic mulch, such as dry wood chips or bark chips.

2. All pine trees over 4 inches in trunk diameter and smaller stressed pines are most susceptible to Mountain Pine Beetle attack.

3. By mid-June, thoroughly spray the trunks of pines greater than 4 inches in diameter, with an insecticide labeled for killing or repelling mountain pine beetle (some insecticides with these active ingredients Permethrin, Carbaryl, Bifenthrin). Spray only green, healthy, pines that have not been attacked by Mountain Pine Beetle.

4. Remove Mountain Pine Beetle attacked pines no later than June each year. Cheyenne residents: Take infested pine trunks and limbs to the City of Cheyenne Compost Facility at 3714 Windmill Road. Cut trunk sections to four to five feet in length. The infested pine trunk sections and limbs will be chipped within two days.

5. Tree Care companies can chip smaller diameter trunk sections and limbs. Trunks too large to chip must either have the bark stripped off, covered with heavy UV resistant clear plastic, buried with eight or more inches of soil cover, or burned prior to the beetles emerging in July.

6. Spraying the trunks of already infested pine trees is not an effective method of killing emerging beetles. Standing pine trees that are successfully attacked, but still have needles on the branches, will have many beetles emerge in July through September attacking the same pine or other nearby pines.

7. Mountain pine beetle carries blue stain fungus, which assists Mountain Pine Beetle in successfully attacking a pine tree by possibly clogging the water transport cells in the tree.

8. Do not bring into the Cheyenne area any firewood or store firewood from beetle killed forest trees or local trees during the growing season, April - October.

9. Burn all firewood from beetle killed trees before April.

10. Left over firewood or recently removed pines in or around the city can be securely covered with two layers of clear 6-mil UV resistant plastic during the growing season (April - October). Do allow beetles to escape the plastic covering. Cover only one layer of logs with the plastic.

Detailed Information on Mountain Pine Beetle:

Mountain pine beetle (MPB) attacks Scotch or Scots pine, Lodgepole pine, Ponderosa pine, Limber pine, and Austrian pine.  A Norway spruce found in Cheyenne, late summer 2007, had been attacked by a bark beetle.  Initially trees are attacked by MPB that are under stress from drought, root or trunk damage, soil compaction, or herbicide damage.  Healthier trees will be attacked as the insect population increases in the area.  Beetles came into Cheyenne inside firewood from trees that had been killed by MPB, usually from mountain forest sources.  

              Keep your pines and spruce trees healthy, water them year-round.

Adult beetles emerge from attacked trees in mid-June through mid-September.  Mid-August on average is the peak emergence time for beetles in ponderosa pine.  The adults fly to green pine trees and chew a hole into the bark.  Sometimes the sap oozing out of the tree "pitches-out" the beetle.  Trees under drought stress or in poor health may not ooze sap. If the attack is successful, a beetle pair mates and the female chews a vertical tunnel where up to 75 eggs are laid.  The eggs hatch and the larvae feed horizontally away from the vertical egg gallery.  The feeding of hundreds if not thousands of larvae will girdle the tree, cutting off the flow of food and water throughout the tree trunk.  MPB adults typically carry spores of blue stain fungus on their bodies.  The blue stain fungus helps weaken the tree by growing in tree cells that function in food and water transport.  The growth of the fungus aids a successful beetle attack by possibly slowing or stopping the sap flow in the tree.  Heavily attacked pines will not die immediately.  A dying tree can stay green for up to 8 to 12 months after a heavy MPB attack. MPB spends the winter protected under the bark in larvae stage and sometimes in adult stage.  In the spring the larvae begin to feed again.  A few adult beetles survive the winter allowing them to continue to lay eggs in the spring or emerge from the trees and attack other trees.  The larvae enter pupae stage in June and July.  Adult beetles emerge from the pupae stage and chew their way out of the tree and fly to green pines.  Several adult beetles may use the same exit hole. The MPB have one generation per year.  

                Water your evergreen trees year-round to help keep them healthy.

Hire a commercial pesticide applicator to spray susceptible pine trunks that have a diameter of 4 inches or larger no later than mid-June with carbaryl (Sevin® and others), permethrin (Astro®, Dragnet®, and others), or bifenthrin (Onyx®).  Thoroughly coat the tree trunk with the insecticide formulation to the point of runoff.  Most of these insecticides should be applied by a professional spray applicator licensed by the State of Wyoming.  A spray application no later than mid-June should provide protection for one adult flight period or one growing season.  Susceptible pines should only need one spray application per year no later than mid-June. Permethrin may need to be sprayed by mid-June and again by early August.

                   Water evergreen trees year-round to help keep them health

Take infested pine trunks and limbs to the City of Cheyenne Compost Facility at 3714 Windmill Road. They will chip infested pine trunks and limbs within two days.

Storing or Transporting Firewood:

Ideally, pine tree trunks destined to be firewood should have stood in place for at least one year after the needles have fallen off of the tree (two years after bark beetle attack), or be well seasoned or dry.  Otherwise, it should be assumed that any pine tree wood has a possible life stage of MPB inside under the bark.  Firewood should be securely covered with one or two layers of 6 mil thick clear plastic tarp treated with UV inhibitors to make the plastic resistant to sun damage.  MPB can sometimes chew through the plastic, but at least the number of beetles attacking green pines will be reduced.  Pine trunks with the bark peeled off can be stored as firewood without being covered.  One layer of thinner UV resistant clear plastic sheet, covering one layer of trunk sections, can also heat the trunks enough during the summer months to kill many of the beetle larvae under the bark.  Transporting uncovered firewood during the adult beetle flight period, mid-June through early October, could spread the beetle from the mountain forest to your yard.  The best precaution is not to transport any wood that could contain Mountain pine beetle during the summer.  

                  To help keep evergreen trees healthy, water them year-round.

Take all necessary precautions from spraying your pine tree trunks to carefully selecting and storing your firewood, or next year's firewood may come from your own yard.

Information adapted from articles by: Colorado State University Extension

Links:

Colorado State University Extension

University of Wyoming - Cooperative Extension Service, publication B-1035 is particularly helpful for tree care. This online publication contains information on: Aphids, Borers, Cottonwood blotch leaf miners, Cytospora canker, Fireblight, Gall makers, Aspen leaf spots, Oystershell scale, Pear slugs, Powdery mildew, and Spider mites.