REPORT OF THE SOCIETY 59 



and the larger and older trees about the residences and near the 

 Observatory are so badly infested that it is only a matter of time before they 

 they will all have to be cut down. As in the case of the locust borer, the 

 injury done at first is of a very insidious character. The fight may be on in 

 full force and the enemy well entrenched before his presence is even noticed. 

 The insects begin their destructive work at the top of the tree and work 

 downwards, killing the upper branches first, giving these the stag head 

 appearance. The trunk and larger branches are then attacked and through 

 these the larval tunnels cross and intersect one with another in endless 

 confusion within the inner bark and sapwood. The characteristic undula- 

 tions thrown up on the outer bark surfaces are sure signs of the mining 

 operations beneath. Here and there rusty, reddish-brown patches appear on 

 the white bark of the trunk and larger branches, indicating the presence of 

 the borer. 



Adult. The adult beetle is a small, slender, dark-bronze insect, about 

 half an inch long and belongs to the family Buprestidae. It does not itself 

 cause any injury, as far as is known, except that it feeds sparingly on the 

 leaves. The time of emergence of the beetles depends greatly upon weath- 

 er conditions. In the northern parts of New York State, where the wint- 

 ers are milder and shorter than those of Canada, the beetles are out early 

 in May, w^hereas in Ottawa the time is later. Last year on account of the 

 wet season the first adult was not seen before June 27. The holes in the 

 bark through which the beetles emerge are of a characteristic shape, some- 

 what semicircular, and can be readily identified. 



Larva. In June the eggs are laid upon or in the bark. The small lar- 

 va on hatching begins tunnelling at once through the bark and sapwood 

 where it forms a cell and remains quiescent for the winter in a remarkably 

 peculiar position, the head and thorax being doubled back on the abdo- 

 men. The follow^ing spring the burrowing operations are continued and 

 the tunnels of the different larvae at work become so inextricably mixed 

 thatitis simply impossible to follow any one particular tunnel throughout its 

 length. The full grown larva is about three-quarters of an inch long, creamy- 

 white, with dark retracted mouth parts. The thorax is particularly wide 

 and may easily be mistaken at first sight for the head. A pair of dark, 

 serrate, chitinous, barbed processess appear on the last segment of the 

 abdomen. Their use is likely to assist the borer forw^ard in the tunnelling 

 process since it is exceedingly sluggish ; or perhaps they act as supports on 

 the walls of the tunnel to prevent the larv a slipping backward. 



Control. So far as is known no satisfactory plan of control has been 

 devised to check the ravages of the bronze birch borer. Insecticides are 



