96 PROTECTION OF PLANTS — 1923-24 



of injufy in at least some cases, points to a long continued association between 

 the protozoa and their plant host. 



L. davidi has been shown to complete its life cycle in certain hemipterous 

 insects. Most probably the forms which I am studying are also associated 

 with insects. Preliminary studies have been made but I have hot yet succeeded 

 in establishing the identity of the forms studied with any of the numerous 

 flagellates to be found in the insects which attack the infected plants. 



THE LIFE HISTORY, HABITS AND CONTROL OF THE LESSER OAK 



CARPENTER WORM. 



by C.-B. HUTCHINGS, 



Asst. Entomologist, Dept. Agriculture, Ottawa. 



For several years past, the red oaks in certain areas of the Ottawa Valley 

 have been attacked by a destiuctive, lepidopterous, wood-boring larva, Prio- 

 noxystus macmurtrei Guer.-Men., commonly known as the Lesser Oak 

 Carpenter Worm, which has caused considerable injury to the trees and been 

 responsible for much loss. 



The caterpillar feeds upon the red oak almost entirely, its tunnelling work 

 being carried on extensively within the bark and sapwood, and later on into 

 the inner heart wood of this handsome shade tree, where it takes the form of 

 deep auger-like holes through which rain water and fungous spores often find 

 entrance. 



The economic importance of this pest made it of special interest; hence a 

 detailed study of its life-history and habits was considered worth undertaking. 



GENERAL PLAN OF WORK AND METHODS 



The place where the work was carried out was at Queen's Park, a small 

 wooded area in extent between sixty-five and seventy acres, situated on Lake 

 Deschenes about two miles west of the town of Aylmer, Que., and about ten 

 miles north-west of Ottawa city. The trees in the park for the most part were 

 red oaks, although there was a good supply of bur oak, maple, basswood, 

 blue beech, poplar, birch, cedar, white pine, spruce and balsam. Numerous 

 evidences on all sides pointed to the fact that the Oak Borer had been at work 

 for some considerable time. Many of the trees were badly scarred and showed 

 ugly bulging trunks; others had become rotted at the base; while the majority 

 had larvae working in them, as shown by the fresh piles of saw dust seen 

 around them. The conditions therefore for making this study were vera favour- 

 able. 



Field work was begun in the autumn of 1918 and continued throughout 

 the summers of 1919 and 1920, supplemented by observations made in 1921 

 and 1922. 



