THE POPLAR AND WILLOW BORER 



477 



Another point that should be brought out here is that the four trees 

 treated with carbolineum in the experimental plot in 1913-14 were not 

 attacked during the summers of 1914 and 1915, and only a single larva 

 was found in them during 1916. This would indicate that carbolineum- 

 treated trees are not readily selected by the females for oviposition, pro- 

 vided untreated trees are available. This point will be further investi- 

 gated by the writer. 



TABLE 3. RESULTS OF EXPERIMENTS OF 1915-16 



* In determining the infestation of the treated trees, not all the 14,000 trees were examined. Rows 

 \vere selected in different parts of the block and every tree was examined carefully. In this way 1161 

 trees were closely scrutinized and not a sign of borer work could be found. The figures in the table are 

 based on the result of this examination. In the second examination a single larva was found at work 

 on one of the treated trees, but as this was the rare exception the fact has been ignored in the percentage 

 column. 



TABLE 4. RESULTS OF EXPERIMENTS OF 1915-16 



* Only 1560 trees were examined, but these were selected rows and the percentage of infestation is fairly 

 accurate. 



The results of the treatment of the second block of about an equal 

 number of trees are shown in table 4. In this block the results were 

 extremely interesting, showing most conclusively the effectiveness of the 

 carbolineum treatment. The writer visited this nursery and showed the 

 owner the method of treatment but did not further supervise the work. 

 In treating the trees on the following day the workmen failed in many cases 



