THE CANADIAN ENTOMOLOGIST. 59 



Forest-insect Explorations in the Summer of 1902. 



[revised by DK. HOPKINS FROM THE STENOGRAPHIC NOTES.] 



Dr. Hopkins gave an account of his preliminary survey, during the 

 past summer, of the forest regions of different sections of the country to 

 determine the primary enemies of forest trees and locate the areas of 

 principal depredations. Between July and November he was in 27 States 

 and two territories. His first trip was made through the South-eastern 

 States, to determine the area of a recent outbreak of Dendroctonus 

 frontalis. He found in the southern Appalachian region that this, one of 

 the most destructive insects of American coniferous forests, was com- 

 mencing its ravages as it did a few years previous to the great devastation 

 wrought by it in the Virginias. He spoke of the probability that some of 

 these insects, which are for a long lime exceedingly rare, then suddenly 

 make their appearance in vast numbers, taking the character of an inva- 

 sion, are varieties of the typical forms which, on account of favorable 

 variations, are capable of extending their range into new areas, and also to 

 overcome the resistance exerted by the living trees attacked by them, 

 which could not be overcome by the typical forms. He gave as an ex- 

 ample the results of his study of Detidroctonus frontalis, in which he 

 found that the form which was so exceedingly common and destructive in 

 the Virginias was a variety of the form described by Zimmerman many 

 years ago. 



After locating the trouble in the vicinity of Fletcher's and Tryon, 

 N. C, he travelled southward through South Carolina and Georgia to 

 Tampa, Florida, and returned by another route, to determine the extent 

 of this new outbreak. Returning to Washington from this trip, he pro- 

 ceeded to the Black Hills, in South Dakota, where a vast amount of pine 

 timber has been killed by Dendrocto?ius fonderosce,3.?, has been mentioned 

 in Bulletin 32, new series, Division of Entomology. This species, he 

 said, is another example of apparent variation from a western type, D. 

 tnonticola, Hopk. MS. It has distinctive and constant characters of 

 structure and habit which are sufficent to entitle it to the rank of a species, 

 and he believes that it is possibly of recent development. D. vionticola 

 attacks the mountain pine ( Fifius vionticola) in Idaho, and the sugar pine 

 (P. Lambertiana) in Oregon. The smaller size of this species, the more 

 primitive character of its gallery, and its wider distribution, indicate that it 

 is the stock from which Dendroctonus ponderosa: has sprung. The latter 

 is apparently more restricted in its range, having been found only in the 



