1916 ENTOMOLOGICAL SOCIETY. 35 



several years earlier. Up to the present time I have records of its presence at 

 the following additional places : St. Catharines, Grimsby Beach, Grimsby, Winona, 

 Fruitland, Guelph, Elmira, Willow Grove near London, Toronto Island, Port 

 Hope, Trenton, Hillier (Prince Edward County) and Montreal (Quebec). 



There has been very little opportunity to examine other parts of the Province, 

 but the above localities show a very wide distribution throughout the Province, 

 especially along the great waterway on the south. It is apparently, however, not 

 yet all over the Province, because I have been in several localities where there 

 seemed to be no evidence of its work, and Dr. E. M. Walker tells me that he 

 has not seen any evidence of injury from it at Lake Simcoe. Montreal, near 

 which Mr. Swaine reports its presence, seems to be the only place it has been 

 seen in Canada east of the Province of Ontario, though very likely it is present 

 in several localities but has not been noticed. 



Host Plants. 



In Europe this insect attacks several species of willows and poplars and also 

 a few species of birches and alders, including our common alder (Alnus incana). 



In the United States a perusal of the writings of Jack, Kirkland, Webster, 

 Chittenden, and Felt, show that scarcely any species or variety of poplar or 

 willow, whether native or imported, is entirely exempt and that the birches {Betula 

 pumila and B. nigra) are also occasionally attacked. I do not remember seeing 

 any definite record of its having been found in alders. 



In Ontario I have devoted every opportunity I could get to discovering the 

 host plants and the degree of infestation of each. Prof. Howitt has assisted me 

 greatly in determining the species whenever I was in doubt. I find that the insect 

 prefers Balm of Gilead {Populus candicans) and Balsam Poplar (Populus halsami- 

 fera) to any other variety of poplar, but that it is sometimes quite abundant in 

 Carolina Poplars, especially where the above species are not present. At Guelph 

 the Balm of Gilead is severely infested in a small clump of poplars on the College 

 grounds, but the other poplars in this clump, consisting of the Carolina, ^Vllite, 

 Large-toothed and Lombardy species, are untouched. By the edges of a woods not 

 far away from the College the Balsam Poplars are much injured by the pest, but 

 the American iVspens alongside them are uninjured. The same was true of the 

 aspens near infested Scrub Willows in the swamps. 



Of the willows the worst infested are our native Scrub WiDows found so 

 abundantly along streams. A tree willow, whose species could not be determined 

 at this season of the year, was also severely attacked. This willow grows 25 feet 

 or more in height, has not so large spreading branches as the Golden or "Wliite 

 Willow {Salix alba) or the Crack Willow (Salix fragilis) but has much more 

 slender and drooping branchlets and smaller, more delicate leaves. It is evidently 

 a native species. One ornamental Weeping Willow in a lawn at Winona was 

 killed by this borer last year. It was the dark-bark type of Weeping Willow, 

 apparently an imported tree. Of the other willows we have not seen more than 

 a very light infestation on the Crack Willow, and the White Willow has been 

 entirely uninjured, as also the Glossy Willow (Salix lucida). There are not 

 many Babylonian Willows to be found, but so far they too have been uninjured 

 wherever examined. 



Comparing what we have observed in Ontario with what has been written 

 of the host plants in the United States, it seems quite clear that Balm of Gilead, 

 Balsam Poplar, and our native Scrub Willows, along with one or two native 



