Montana-Northern Idaho Pest Action Council (Cox 1968) resulted in identification of 

 a chemical attractive to the mountain pine beetle (Pitman et al . 1968). This research 

 is directed toward manipulation of mountain pine beetle populations to reduce losses 

 in the western white pine type. 



Although tests have shown beetle response to pheromones, the practical field use 

 of these chemicals has not been demonstrated. Atkins (1968) points out a number of 

 obstacles to successful field use, particularly lack of understanding many of the basic 

 physiological -behavioral aspects of bark beetle ecology. 



LONG TERM MANAGEMENT GOALS AND PLANS 



The management of lodgepole pine is handicapped by such factors as mountain pine 

 beetle infestations, dwarfmistletoe infections, and lack of sufficient markets. Markets 

 can and will develop with increased demands for timber and shortage of supplies in other 

 areas. Dwarfmistletoe infections can be controlled through proper cutting methods and 

 treatments applied to the cutover areas. However, in the absence of wholly effective 

 control methods, the mountain pine beetle is apt to remain a threat to the lodgepole 

 pine resource. 



Acceptable Risk 



Every forest management action assumes some calculated risk and growing lodgepole 

 pine trees in the face of mountain pine beetle depredations is no exception. For 

 example, as seen in figure 1, the probability of an 18-inch tree surviving a beetle 

 epidemic is practically zero, whereas 12-inch trees have about a 50-50 chance of surviv- 

 ing and 10-inch trees show about a 70 percent chance of surviving. 



Data presented from the reconnaissance of the 42 stands in the Targhee-Teton- 

 Yellowstone area show that approximately 86 percent sustained one or more infestations. 

 Therefore, the probability of a stand being infested in this area appears to be rather 

 high. If we assume 86 percent probability of infestation in the stand and 50 percent 

 probability that the 12-inch trees will be infested, then the product of these two 

 (86 X 50 = 43 percent) would provide an empirical estimate of the probability of loss. 

 On this basis there is about a 57 and 74 percent probability that 12-inch and 10-inch 

 lodgepole pine trees, respectively, will not be killed by the mountain pine beetle. 

 The utility of these probabilities is only to illustrate the point, but their applica- 

 bility to other lodgepole areas is questionable. Much variability exists in the 

 probabilities even locally, so widespread use of these values is not recommended. 



Although the probability of attack by tree age is not known, nevertheless age and 

 diameter are correlated so that probabilities by diameter classes do reflect age 

 relationships . 



As previously stated, the probability of infestation varies by habitat type. For 

 example, in the Abies lasiocarpa / Vaccinium scoparium habitat type the probability of an 

 infestation occurring is about 44 percent (figure 3). However, the probability of an 

 active infestation in the Abies lasiocarpa/Pachistima myrsinites habitat type exceeds 

 90 percent. Therefore, habitat types must also be taken into account when considering 

 risks to be assumed in management. For example, the risk of growing 16-inch trees on 

 the Abies lasiocarpa/ Pachistima myrsinites habitat type would be very high (92 X 82 = 

 75 percent probability of loss) where only 25 percent or less of the 16-inch trees 

 could be expected to survive. On the other hand, a 44 percent probability in the 

 Abies lasiocarpa/Vaccinium scoparium habitat type would present a brighter picture 

 where (82 X 44 = 36 percent loss) 64 percent or nearly two-thirds of the 16-inch trees 

 could be expected to survive. 



19 



