104 THE REPOKT OF THE No. 36 



The Adult Beetle, The adult beetle is slender, somewhat flattened, dark 

 olivaceous bronze in color and slightly less than half an inch in length. 



The beetles emerge from the bark of the infested trees during June and July. 

 At Ottawa this season, the first adult appeared in our cages on June 27th, and the 

 first adults were taken on trees in the open on June 30th. The early part of the 

 season was very wet, and the emergence of the beetles was undoubtedly retarded 

 thereby, since heretofore we have found adults emerging as early as June 9. The 

 date of emergence will vary considerably with the season, the locality and the 

 latitude. It is possible that in the Niagara Peninsula beetles may sometimes 

 emerge as early as the middle of May, since they are recorded from Ithaca, N. Y., 

 as early even as May 1st. The beetles were found on the trees at Ottawa this season 

 until July 28th. 



The beetles were reported by Larsen as feeding freely npon leaves of willow, 

 poplar, birch, elm and other trees. In our experiments they have fed very sparingly 

 upon birch leaves, but could not be induced to feed at all upon willow, poplar or 

 elm. Neither could we find any evidence of their feeding in the open upon those 

 trees, nor to any considerable extent upon birch. We hoped to obtain a partial 

 control by poisoning the adults, but so far have not been successful. 



The Larval Mines. The females were frequently observed feeling with the 

 ovipositor beneath bark scales, evidently searching for a suitable place for oviposi- 

 tion. Such places were marked and carefully examined, but neither in the field 

 nor in our cages were we able actually to find the eggs. However, the newly started 

 tunnels in the branches are easily traced backward to minute openings through 

 the outer bark through which the freshly hatched larvfe have entered. It is 

 evident that the eggs are deposited usually beneath the scales on the rougher 

 portions of the bark of the branches and trunk. The larvfe enter the bark through 

 minute openings, and bore directly inward through the bark to the wood surface. 

 The tunnel is then continued between the bark and wood for a short distance, and 

 is further continued in a winding or zigzag manner partly below the wood surface 

 and partly between the bark and wood. Early in the autumn the mature larvae 

 excavate elongate hibernating cells in the ends of the tunnels a short distance below 

 the wood surface, in which they pupate in the following season and emerge through 

 the characteristic part-oval holes in the bark. In these cells the larvfe are folded, the 

 cephalic third being bent over and closely pressed to the remainder of the body. 

 At the close of the season there are, however, many smaller larvae in the branches 

 not more than one-half grown; these hibernate in normal tunnel-ends immediately 

 below the bark, and continue their development the following season. There is 

 evidence that in some individuals at least the life cycle lasts- for two seasons. 



Control Measures. The only method of control that we can safely recom- 

 mend at present is to cut out all infested birches and burn the entire tree, including 

 the small branches, before the middle of May. By the time the top of the tree 

 is dead from the action of the borers, it is useless to attempt to save the tree, since 

 the grubs are then distributed over most of the trunk and branches, as will be 

 evidenced by the reddish patches upon the bark. All that can be done is to pre- 

 serve for three or four years a mutilated relic, and at the same time retain an ideal 

 breeding ground for the beetles from which they will spread to the remaining 

 birches of the neighborhood. 



The results of the most promising of our control experiments will not be 

 definitely determined for another year or longer; and in the meantime we can 

 only urge owners of ornamental birches to watch carefully for evidence of the 



