92 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



Mr. a. D. Hopkins: I want to compliment the President on the 

 selection of the subject of his address and his treatment of it. The 

 various topics relate to fundamental principles, the importance of 

 which every entomologist should realize. The failure to consider 

 certain general principles and natural laws in connection with our 

 investigations has led to a waste of time in the investigation of 

 unnecessary details and to the recommendations of methods of 

 preventing and controlling insect attack which has led to the waste of 

 money in unnecessary work. 



We should have a better knowledge of the fundamentals and some 

 of us should be devoting our time to the investigation of principles 

 and laws and make the results available to those who are engaged 

 in the investigations of the details. We cannot all investigate these 

 broader problems but some of the older men with broad experience 

 should do so, and they will need the sympathy and support of the 

 other investigators when ideas and conclusions are advanced which 

 are new or radically different from what has been accepted heretofore. 

 There may be, and usually is something in a new idea. Let us first 

 be sure we understand them and then test them out in practice before 

 we discard them. 



It has not been possible for the President to cover the details and it 

 is not necessary that he should in an address of this kind. In the 

 consideration of general principles, we must think in general, not 

 specific, terms. 



With reference to the physiological influences of the host mentioned 

 by Doctor Hewitt, we have found, in our investigations of methods of 

 controlling depredations by bark-beetles in the natural forests of the 

 West, that we must consider every phase of economy as well as 

 efficiency. We have found that the mountain pine beetle {Den- 

 droctonus monticolce Hopk.) will attack and kill the mountain pine, 

 yellow pine, lodgepole pine, and the sugar pine, but that if it becomes 

 estabhshed in one host species, as, for example, the lodgepole pine, 

 through continuous attack of many generations, the beetles — when 

 they emerge-^will not attack nearby trees of any of the other host 

 species but will show a decided preference for the species in which 

 they bred. That is, it will not go from one host to the other in 

 sufficient numbers to be a menace, but will take many years for it to 

 change from one host species to another. Now, where the less valuable 

 lodgepole pine is thickly infested and the area is surrounded by the 

 more valuable yellow pine, which it is desired to protect, we find that 

 we only have to deal with the infestation in the yellow pine, knowing 

 that the infestation in the lodgepole will remain there. This we have 

 proven in many cases of actual practice. Therefore, any money 



