Yearbook^ of Agriculture 1949 



ESTIMATES OF TOTAL VOLUME OF TIMBER KILLED BY PINE BARK BEETLES DURING 

 VARYING PERIODS UP TO 1946 (IN THOUSAND FEET BOARD MEASURE) 



Volume of 



Species Insect Region affected Period timber killed 



Ponderosa pine Western pine beetle . . . Pacific States 1921-46 25, ooo, ooo 



Do Black Hills beetle Rocky Mountains 1895-1946 2, 500, ooo 



Do Mountain pine beetle do 1910-46 5, 500, ooo 



do California 1921-46 3, 500, OOO 



do Pacific Northwest 1921-46 750, ooo 



do Northern Rocky Moun- 1910-46 3, 500, ooo 



tains. 



do Rocky Mountains 1910-46 6,000,000 



do Pacific coast 1921-46 1,000,000 



Sugar pine 



Western white pine. 

 Do.. 



Lodgepole pine. 

 Do.. 



where they occur. Thus detection sur- 

 veys are the first step in any effort to 

 protect forests by controlling destruc- 

 tive insects and diseases. 



The initial procedure in protecting 

 the forest from pests is basically the 

 same as that used to prevent destruc- 

 tion from fire. In many respects, how- 

 ever, pest control differs from fire 

 control. It is well established that oc- 

 currence of infestation or infection on 

 a few trees does not necessarily mean 

 that important destructive loss will fol- 

 low unless control measures are ap- 

 plied. It is important that this be 

 recognized as it has a significant rela- 

 tion to any program of forest-pest con- 

 trol and survey designed to provide a 

 basis for action. It emphasizes the es- 

 sential role of the entomologist and 

 pathologist in the survey program. 

 Facts assembled on the occurrence of 

 forest pests must be appraised on the 

 basis of knowledge of their behavior 

 and development. 



Such appraisal is the second essen- 

 tial step in any program to combat in- 

 jurious forest insects and diseases. It 

 provides the basis for any decision to 

 combat the pest. It has an important 

 bearing on the type of data the survey 

 should develop. 



DETECTION AND APPRAISAL METH- 

 ODS differ with the pests. The wide 

 differences in habits and appearance 

 of the numerous kinds of insects and 

 diseases destructive to forests make it 

 impossible to use any single or simple 



procedure in carrying out inspections 

 to detect their presence and determine 

 the significance of their occurrence. 

 Methods used in making surveys will 

 also differ in various sections of the 

 country. Practices will necessarily dif- 

 fer with the objective sought. 



To PROTECT WHITE PINE from the 

 destructive introduced disease white 

 pine blister rust the detection of the 

 disease organism is secondary to the 

 location of the currant and gooseberry 

 bushes on which the disease must spend 

 part of its life. The spores of the disease 

 produced on white pine are hardy and 

 remain viable much longer, even when 

 carried long distances. Protecting 

 white pines from the disease is largely 

 a matter of detecting and destroying 

 currant and gooseberry bushes that 

 grow among or adjacent to the pine 

 trees. Hence, surveys for currants and 

 gooseberries are a part of white pine 

 blister rust control. 



IN THE CASE of another introduced 

 pest the gypsy moth where its 

 eradication in designated areas is the 

 objective and the basis of preventing 

 natural spread to new sections, inspec- 

 tions for the insect pest must be de- 

 tailed and provide complete coverage. 

 Research has developed ways to do 

 this effectively and without undue 

 cost. An important feature of such 

 surveys includes application of knowl- 

 edge that the winged free-flying males 

 are attracted to extracts made from 



