148 Bulletin 234. 



former or alba was first attacked, the infestation then extending to the 

 cut-leaved variety. But I have seen a case in Ithaca, where a cut-leaved 

 birch was killed before a tree of the whole-leaved form only a rod or 

 two distant showed any signs of being infested. 



Several trees of the American black (Betula lenta) and the yellow 

 (Betula lutea) birch have been killed by the insect in Buffalo, and it is 

 also recorded as attacking the paper or canoe birch (Betula papyrifera). 



However, there is no record of any kinds of birches having been 

 killed by the insect in forests or woodlands. It seems to have confined 

 its destructive work to the more valuable individuals and groups of these 

 beautiful trees set in parks and private lawns. 



The beetles have been taken on poplars cut and piled by the roadside, 

 on poplar sprouts and trunks, and on willow, but there is no evidence 

 that the insect was breeding in poplar. Larsen put a number of the 

 beetles in a cage and supplied them with fresh leaves. " When only 

 birch leaves were supplied they fed very sparingly. Some elm leaves were 

 then put in with the birch and they fed greedily upon these. This led 

 to further experiment and various sorts of leaves were used. They fed 

 upon almost any leaf of soft texture. But their favorite food was willow, 

 poplar and aspen leaves with preference strongly marked in the order 

 given. It seems from this that the beetles upon leaving the birch feed 

 on other trees until the time for reproduction." 



The Life and Habits of the Insect 

 The chain of evidence regarding the life-story of this bronze birch 

 borer is not yet quite complete, but from the records and from my 

 observations and investigations most o*f the details can be supplied. 



Hibernation. — All the evidence I have, shows that the insect always 

 passes the winter as a full-grown grub or borer curled up in a long, 

 narrow cell or chamber, which it makes in the wood not far from the 

 bark. I have failed to find smaller borers in uncompleted burrows in 

 autumn. One of these hibernating cells is shown at c in Fig. 36. Most 

 of the borers may be found in these cells early in October ; Adams 

 reports finding some as early as July 14th. Some of them can be easily 

 located by cutting into the tree beneath the characteristic rusty colored 

 spots (Fig. 30, a). The grubs rest in the cells in a peculiar manner 

 with the cephalic third of the body bent around l\ing close to the re- 

 mainder. They are very sluggish when removed from the cells. Early 

 in the spring these hibernated borers shorten up. straighten out in their 

 cells, and thus prepare for transforming. 



Transformation and habits in spring. — During the latter part of 

 A.pril or early in May. depending upon weather conditions, the grubs 

 transform in their hibernating cells into adult insects or beetles (Figs. 



