1917 



ENTOMOLOGICAL SOCIETY 



123 



Although considerable biological data have been gathered in the course of this 

 work, only the control experiments and their results wil be discussed here. Since 

 the publication of Schoene's Avork in Bulletin 2HG of the New York Experiment 

 Station, at Geneva, very little has been done in reference to this insect. As the 

 result of his work he recommended the use of Bordeaux mixture containing an 

 arsenical. This spray should be applied during late July in' order to destroy the 

 adults which feed indiscriminately on the bark of the trees. Owing to the diffi- 

 culty of spraying nursery trees this recommendation has not been adopted, and I 

 know of no experiments which have been conducted on a large scale in order to 

 test the efficiency of this method. 



To present the method of experimentation more clearly a brief synopsis of the 

 life cycle of C. lapathi Linn, is necessary. The egg^ are deposited in August, 

 September and October in two or ihree-year-old stock in the nursery rows. I did 

 not succeed in finding eggs in younger stock. The cgg^ are laid exclusively in the 

 corky portions of the tree, just below the surfae.-" of the bark near the cambium 



Egg in situ. 



Larva, just hatched. 



layer. They were found most commonly around Jenticels, near buds and branches, 

 or in growths caused by pruning. These eggs hatch in late August, September and 

 October. The young grubs feed on the bark and grow slightly before hibernation. 

 In these small chambers, just below the surface of the outer bark, the young larvae 

 pass the winter. Feeding begins early in the spring, the larvae attacking the 

 cambium layer and often girdling the trees. In late June they bore into the heart 

 of the trees, forming the pupal cells. Pupation takes place during July and the 

 adults begin emerging in late July and August. The beetles feed for a short time 

 before beginning to oviposit. 



Up to the time that the writer undertook Avork on this insect no efficient 

 control measures liad been devised. The general recommendations had been the 

 cutting out and destruction of infested trees. Sciioene in Bulletin 286 of the New 

 York Experiment Station stated that the use of arsenicals during July and August 

 would poison the greater majority of the beetles and reduce infestations in nurseries. 

 In practice it has been found tliat though Paris green and lead arsenates were used 

 in large quantities it had no effect in reducing the annual loss. At the time (1914) 

 the author began to look into this problem several large nurseries in New York 



