522 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



EXPERIMENTS IN THE CONTROL OF THE POPLAR AND 

 WILLOW BORER (CRYPTORHYNCHUS LAPATHI LINN.) 



By Robert Mathesox, Ithaca, N. Y. 



The poplar andmllow borer is a serious pest in nurseries of New York 

 state and at present is doing much damage. It is also a serious pest 

 to ornamental poplars and mllows, including basket willows. The 

 most extensive depredations of this pest occur in nurseries where large 

 blocks of these trees are grown, and in some cases the annual loss is 

 very considerable. Dming the past two years, as time would permit, 

 control experiments have been conducted in two of our large nurseries. 

 This work has been made possible through the courtesy of the propri- 

 etors, and to them I desire to express my thanks. 



Although considerable biological data have been gathered in the 

 course of tliis work, only the control experiments and their results will 

 be discussed here. Since the pubhcation of Schoene's workin Bulletin 

 286 of the New York Experiment Station at Geneva yery 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 apphed during late July in order to destro}^ the 

 adults which feed indiscriminately on the bark of the trees. Omng to 

 the difficulty of spra^dng nursery trees this recommendation has not 

 been adopted, and I know of no experiments which have been con- 

 ducted 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 eggs are 

 deposited in August, September and October in two- or three-year-old 

 stock in the nursery rows. I did not succeed in finding eggs in younger 

 stock. The eggs are laid exclusively in the corky portions of the tree, 

 just below the bark in the cambium layer. They were found most com- 

 monh^ around lenticels, near buds and branches, or in growths caused 

 hy pruning. These eggs hatch in late August, September and October. 

 The 3^oung 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 

 larvse attacking the cambium laj^er 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. 



Early in my observations I was led to the conclusion that this insect 

 could be destroyed by some contact spray applied to the trunks of the 

 trees in the autumn after the leaves have faUen, or in the spring before 



