36 



THE REPOET OF THE 



No. se 



tree willows, are the favorite food plants. Next to these would appear to be the 

 Carolina Poplar {Populus deltoides). 



No alders were found infested even when in the midst of infested scrub' 

 willows. Birches have also appeared to be exempt in Ontario. 



Nature of the Injury. 



The photographs show sufficiently well the sort of injury done. It is all 

 caused by the larvae. These work both in the sapwood and heartwood in older 

 trees and in the heartwood of very small trees. The borers seem to prefer the base 

 of the smaller trees, but they are found on larger trees as high as 15 feet or 



Cross section of a young poplar and of a larger willow tree, near 



the base, showing the work of the borers. (About 



natural size.) 



Longitudinal section of a poplar tree, showing tunnels made by the 

 larvae. (Slightly reduced.) 



