1917 ENTOMOLOGICAL SOCIETY. 105 



presence of this destructive borer, and to ndopt promptly the drastic measures that 

 seem at present necessary for saving the remaining trees. 



Parasites. The larva* with which we worked this summer were very heavily 

 parasitized, while the numl)er of beetles to be found on the trees in the open was 

 surprisingly small. The birches about Ottawa apparently have been dying more 

 slowly during the last few years than heretofore, and it is possible that this may be 

 accounted for by an increase in the number of the parasites. 



Proi-'. Caesar: I should like to ask i\lr. Swaine how many species of birch 

 are attacked by the Bronze Birch Borer. 



]\Ir. Swaine: We have a considerable number of species of birch in the 

 Arboretum where our work was carried on, and there is a distinct difference in the 

 species in the degree of immunity to attack by borers. We find the native species 

 attacked and even killed when in isolated conditions under cultivation; out in the 

 woods I find the native birches attacked by the borers not infrequently, but have 

 never known the trees to be killed under such conditions. In connection with the 

 Alder Leaf-miner we find that the different species and varieties of Alnus differ 

 widely in their susceptibility to attack; some are very badly infe.-ted, and some 

 show little or no evidence of injury. 



Dr. Howard: I was out in Ashland, Oregon, last summer, and for the first 

 time saw the method of determining the damage by Dcndroctonus beetles at a dis- 

 tance. Our man was al)le to point out at a distance Dendroctonus-injured trees. 

 I was interested in Mr. Swaine's statement about the killing off of the new growth 

 by the severe weather of last winter, and I was wondering whether it was possible 

 to detect this killing at a distance, and to distinguish it from Dendroctonus-killed 

 timber. I should be interested to liave Mr. Swaine tell us just what the difference is. 



Mr. Swaixe: The frost-injured trees are usually in a definite belt situated 

 along the sides of the mountains, and the effect may 'be seen for years, although 

 most of the trees may recover. On Mt. Pundle at Banff", Alberta, there is a belt 

 of such injury still showing, which occurred nine 3'ears ago. In the early season 

 following the injury, the foliage appears yellow and gives a decidedly yellowish 

 tint to the belt; in some cases many of the trees actually die. One sees this injury 

 in a definite belt between certain altitudes on the upper benches. The Dcn- 

 droctonus injury on the other hand appears as clumps of dead trees, '' red-tops,'' 

 with isolated dead trees here and there. There may 'be from three or four to 

 fifteen or thirty red-tops, or more, in each clump, with here and there isolated trees. 

 The injury is quite characteristic in the earlier stages. 



^Ir. Harrixgtox: Does a small moth that appears in terminal twigs of 

 the yellow pine do much permanent injury? It disfigures the trees greatly by 

 forming large masses of gum, and appears in the terminal shoots. Have you per- 

 formed any experiments with this insect? 



Mr. Swaixe: I do not think that species does very much damage except in 

 disfiguring the trees. There is one particularly injurious species known to me 

 occurring in southern British Columbia affecting yellow pine. Xoar Okanagan 

 Landing there is a lariro patch of timber in which many trees are badly injured 

 or killed by a species which bores in the cambium of the branches, not in the trunk, 

 but around the 1 'ranches so that it girdles and kills them. Of course all through 

 that country there is the injury to the tops caused by boring caterpillars. 



Mr. Harringtox: Js the black pine attacked also by Dcndroctonus? 



