186 



MR. BARRUS, of New York : I would like to ask: Is there 

 any case where the larva of the insect is fonnd nnder the bark, 

 and the mycelium of the fungus is found radiating from the 

 burrow of that insect? I would like to know whether that is 

 known to Dr. Hopkins, and whether tliat means anything rela- 

 tive to the spread of the disease? Would it be possible that the 

 spores of the fungus were deposited at the same time the insect 

 was deposited there in tlie egg, and a mycelium growth had gone 

 on parallel with the development of the larva? 



DR. HOPKINS: That is a problem yet to be solved. It is 

 a problem in Avhich we will have to co-operate with the forest 

 pathologists. We are studying that feature of the problem. We 

 find insects undoubtedly associated with the disease. We find 

 them going into the perfectly healthy bark of some trees and we 

 find the disease following them. We find also that insects go 

 into the healthy bark or other trees, and the disease does not 

 follow; so that it is one of the complex problems to be worked 

 out. 1 think it is absolntely necessary to work out a few of these 

 problems before we can do much towards control. I think it will 

 save monej^ We certainly ought to know something about what 

 we are doing. 



MR. BARRUS : A number of articles have been sent in for 

 identification, reported as the work of insects which had not 

 worked in healthy trees, and I wondered whether it was meant 

 by that whether those insects would work on a tree after it had 

 lost a certain degree of vitality, even before the tree had died. 



DR. HOPKINS : It depends on the species. There are very 

 few people who can recognize the different species of insects in 

 the larval stage. We have specialists working on this now. The 

 identification of species from the larval stage is something the 

 general entomoligist cannot do. Any assumption, from the larval 

 form alone, that certain insects will do so and so, is mere guess- 

 work. Some species of insects will bore in the living bark. Others 

 can not possibly exist in the living bark but must bore in the 

 dying, dead or decaying bark. There are many species, as this 

 list shows, over four hundred and seventy-two species, and out 

 of those there are only a very few which attack perfectly healthy 



