124 



THE KEPOET OF THE 



No. 36 



State had about concluded to cease raising Carolina poplars although there was a 

 steady demand for such stock. 



Early observations led the writer 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 fallen, or in the spring before the young larvae have begun 

 actively feeding. This seemed very reasonable, owing to the quite exposed con- 

 dition of the young larvse in their burrows. It seemed ihat some of the emulsions 

 ought to penetrate the outer bark or be absorbed through the very small amount of 

 frass at the entrance to the burrows and destroy them. With this conclusion, 

 varying strengths of miscible oils and kerosene emulsion applied both in the fall 

 and spring were experimented with. In order to secure a stronger penetrating 

 fluid it was felt carbolineum avenarius ought to be given a thorough trial, but very 

 little is known about the constituents of this preparation. Furthermore, very little 

 is known as to its effects on actively growing or dormant trees. 



In the fall of 1913 seventy-six badly infested two-year-old poplar trees were 

 secured and planted at the insectary. On December 1, 1913, part of this block v/as 

 treated with scalecide at varying strengths and also a few trees with carbolineum 

 and its emulsion' as indicated in the table. This experiment was closely watched 

 the following spring but no injury to the trees could be noted, except that the 

 <3arbolineum treated trees did not seem so vigorous. However, they grew and are 

 now (1916) large healthy trees. Examination and careful count of the burrows 

 in all of the trees was made on June 17, 1914. The number of larvaa present per 

 tree is shown in table I. 



TABLE I. Cryptorhynchus Lapathi, Linn. 



In the spring of 1914 a series of experiments was undertaken in a large nursery. 

 Three-year-old stock was chosen as it was the most available at the time of doing 

 the work. Badly infested trees were selected at one side of a large block which 

 had been recently dug. Directly across the roadway was a block of young poplars. 

 On March 31 scalecide, of varying strengths, carbolineum, and carbolineum emulsion 

 were applied to the trunks from the ground up to the young growth. The day was 

 fair but it began raining before the various treatments 'were completed. However, 

 the rainfall was slight so it should not have had any effect on the insecticidal 

 qualities of the preparations. 



The treated trees were examined carefully on May 14, 1914. The various 

 treatments had no effect on the growth of the trees, every tree growing vigorously, 



'The carbolineum emulsion was prepared as follows: 1 lb. sodium carbonate, 1 

 quart hot water, 1 quart carbolineum avenarius. The sodium carbonate was dissolved 

 in the hot water and the carbolineum was then added, stirring vigorously. 



*A11 dilutions are with water. 



