lecture, but it will probably be necessary to spend about 

 10 cents per acre per year on the average, or J23O,OO0 

 annually. 



The question has been raised more than once as to the 

 justification for so expensive a blister rust control program. 

 A proper answer requires consideration ot the timber values 

 involved along with other timber-growing costs, which 

 have not yet all been presented, and therefore the analysis 

 of this point is postponed to the chapter on economic 

 factors. In this connection it should be remembered, 

 however, that, unlike the damage done by fire, only minor 

 watershed values and only temporary loss in recreation are 

 at stake. It is the timber loss alone upon which blister rust 

 control must be judged sound or unsound as a public 

 investment. 



Forest Insects 



Insect pests of the forest are many and varied. Under 

 normal conditions they cause an important and continuous 

 drain upon the forests. On occasion, under the most 

 favorable physical conditions, the infestation of an indi- 

 vidual species will multiply itself into an epidemic often 

 resulting in very large losses of potential revenue. 



The mountain pine beetle {Dendroctonus monticolae) has 

 lieen the chief insect depretiator during recent decades in 

 this region. Throughout the region it has killed an 

 enormous volume of lodgepole pine, western white pine, 

 and ponderosa pine. In northern Idaho its chief offense 

 has been the killing of much valuable western white pine. 

 It is estimated by the Bureau of Entomology ami IMant 

 Ouarantine that an average of almost 91 million board 

 feet (log scale) of western white pine saw timber has been 

 killed annually by the dendroctonus beetles during the past 

 10 years. 



.\w attempt has been made by the Forest Service on a 

 relatively limited scale to curb tiie rise of these epidemics. 

 In a control program concentrated principally on the Coeur 

 tl'.Alene National I'orest, infecteti trees have been located 

 antl the beetles destro)ed. This approach to the jiroblem 

 is based on the theory that it the infection points can be 

 retluceti, the possibility of flare-up ami large timber losses 

 will likewise be reiluceil. Between l''2.> and I'^.'^H ajiiM-oxi- 

 niateU ;f .Vi 1 ,000 was sjieiit m insect control in northern 



Idaho. Except for J2,000 of private funds it was all 

 Federal money. The average for recent years has been 

 $35,000 annually. 



Too few factors can be pinned down to make it possible 

 to assay the exact value of control efforts. Some of the 

 timber killed is overmature, and in such cases the imme- 

 diate cause ot death is not important, for if bugs do not 

 do it something else will. The same thing applies to some 

 of the young timber. In the normal young stand, com- 

 petition is continuously eliminating individual trees as 

 the available growing space decreases. These trees 

 softened by competition may be finished off by insects or 

 disease. Any insect-control work on trees which would 

 die in a year or .so anyway would obviously have no 

 justification. The value ot control lies in preserving till 

 time of harvest those trees capable of living 20 to 50 years. 

 Experts agree that past insect-control work has saved 

 much of such western white pine and that the money has 

 been well spent. 



In setting up a reasonable insect-control program tor 

 the future, the factors which have already been mentioned 

 should be considered and also the tact that the cost ot con- 

 trolling attacks in certain areas would be too expensive to be 

 practical. Ninety-one million board feet is the estimated 

 annual loss ot western white pine from Dendroctoyius monti- 

 colae in northern Idaho. The Bureau ot Entomology and 

 Plant Quarantine estimates that it is economically feasible 

 to control infestations sufhcientlv to prevent the loss ot 

 45 to 50 percent of this timber. The possible cost of 

 $150,000 annually is considerably lower than the stumpage 

 value ot the timber saved tor later logging. Even it the 

 cost equalled the stumpage value, the community would 

 benefit b) the $25 or $30 per thousand board teet produced 

 in the manufacture ot this timber. The Bureau feels 

 that it is consarvative in setting the upper limit ot annual 

 control expenditures at $100,(XX), which is about $65,(XX1 

 more than is being spent at present. 



.As the road systems ot northern Idaho become more 

 completely developed, it will be possible through partial 

 logging to utilize many trees that would otherwise be lost. 

 With control by utilization on some areas, the amount of 

 money needed for the present kind ot contn>l would 

 decrease. 



39 



