410 JOURNAL OF FORESTRY 



sufficient period of years to completely eradicate the insects causing the 

 damage. The determination of the flight habits of the insects belong- 

 ing to this genus is, therefore, an important point for solution. 



Our present silvicultural efforts looking ultimately to bringing our 

 forests under sustained yield are largely confined to the removal of the 

 present stands of mature and overmature timber in which the annual 

 losses equal or exceed the increment with the idea of substituting thrifty 

 growing stock. It has been shown that insect enemies are almost en- 

 tirely accountable for the dissolution of stands of western yellow pine, 

 and so far as possible cutting operations should, therefore, be directed 

 toward the removal of timber from those stands in which present 

 infestation is at its worst. 



The manner in which this cutting is undertaken will have an im- 

 portant bearing on the life history of the succeeding stand, the stand 

 which we hope to bring under management. If the actual infestation 

 present is not reduced by the cutting operations it necessarily follows 

 that the proportionate loss in the reserved stand after cutting will be 

 greater than the ratio of the loss before cutting was to the uncut stand. 

 Investigation is urgently needed to determine what, if any, relation 

 exists on western yellow pine timber sale areas between the disposal 

 of brush, logging debris, cull logs, etc., and subsequent infestation in 

 standing timber and reproduction. At the Ashland conference last 

 November there was a general agreement among the men present that 

 the losses in the reserved stand on western yellow pine sale areas was 

 a real problem in Oregon, California, Arizona, and New Mexico. It 

 will be noted that Colorado is omitted from this summary, as our 

 observations, or possibly lack of observations, have not shown this 

 subject to be a serious one. It does not seem to me that we are immune 

 to a condition which is so widespread, and I believe an examination of 

 the cuttings made in this type may show our losses to be greater than 

 we now suppose. 



The impression seems quite general that our insect losses are due 

 to the maturity of the stands, and that with the removal of the present 

 overmature timber and the substitution of a young and thrifty stand 

 our losses will auomatically decrease. If such is our conclusion I 

 am afraid we are going to be disappointed. Unfortunately the Den- 

 droctonus beetles do not use a nice discrimination in the selection of 

 trees they attack. It is true that they do seem to have a propensity 

 for selecting fresh lightning-struck trees, but they by no means confine 

 their activities to trees in this condition, even where the supply is large. 



