66 



PROTECTION" OF PLANTS. 1916-17 



The Injury. As already seen the injury to the tree is done in the larval 

 stage. The wounds made from time to time in the bark and sapwood often 

 cause girdling, the branches frequently breaking off as a result of this. 

 Where the tree is badly honey-combed it is rendered entirely unfit for 

 commercial purposes. The healing scars on the bark surface, caused by the 

 tree in its endeavour to patch up the injury done by the young grubs in the 

 fall, give to the trunk an unsightly appearance and often times these rough- 

 ened areas provide ground for injurious fungi to become established and 

 permit the dampness and rot to enter the tree. The carpenter ants also 

 obtain entrance through the holes made by the beetles and help to complete 

 the destruction of the tree. 



Control Measures. A number of experiments of various kinds have 

 been carried out from time to time such as: — 



(a) Collecting adult beetles from golden rod which had been planted 

 especially for the purpose. 



(b) Digging out the young larvae shortly after they had begun their 

 work. 



(c) Applying different washes, such as soap solution and carbolic acid, 

 whitewashing trunks of trees, etc. 



(d) Employing poisoned baits. 



All these, individually, or taken more or less together have been found 

 to give fair results. But the only sure method of control, where bad infesta- 

 tion occurs, is to cut the tree down and burn it. 



A considerable amount of work was done last year at Ottawa in connec- 

 tion with the life history and control of Cyllene rohiniae and it is expected 

 this coming summer further \aluable dat& will be secured, especially along 

 the lines of control. 



The Bronze Birch Borer 



The birch is one of the most beautiful and most graceful of our orna- 

 mental trees and for this reason is grown extensively in parks and gardens. 

 Unfortunately, under cultivated conditions, the various species of this tree 

 are most subjected to the attack of its greatest and most destructive enemy, 

 the bronze birch hover A grilus anxius. Under more natural conditions, as 

 in the forest, this does not occur. 



The Injury. Throughout Ottawa city, in private gardens and on the 

 Driveway, the work of this beetle is very noticeable. At the Central 

 Experimental Fami, nearly all the birches in the Arboretum are affected 



