470 



STATE BOARD OF AGRICULTURE. 



percentage of the total number of borers actually on the tree was killed. 

 These trees had trunks with rough bark and many old wounds and it was 

 around these wounds high on the trunks and in the crotches that most of the 

 borers were present. The check trees, as shown in the table, had a very low 

 infestation in the lower part of the trunks and in the crowns. 



SUMMARY. 



In all these experiments, the borers which were in such a position that they 

 could be affected by the para-dichlorobenzene, were effectively controlled. 

 On trees with smooth trunks and few wounds, most of the borers were low 

 enough to be effectively treated but on older trees with rough bark and many 



Fig. 20. — A tree which has been treated with para-dichlorobenzene and the borers controlled without 

 digging or "worming" them out. The tree is left in sound condition, 



wounds along the trunks and in the crotches, a large proportion of the borers 

 were too high to be subject to this treatment. 



Injury to trees. There has been no evidence of injury to treated trees by 

 para-dichlorobenzene in any of the experimental orchards. The trees were 



