REPORT OF THE STATE ENTOMOLOGIST I915 71 



AN OIL COMPOUND AND YOUNG TREES 

 Insect injuries to trees have been exceptionally serious during 

 the last few years in the vicinity of New York City. This has been 

 especially true of the hickory bark beetle, Eccoptogaster 

 quadrispinosa Say, and the lined chestnut borer, A g r i 1 u s 

 bilineatus Weber, and as a consequence various methods have 

 been recommended for controlling these insects or destroying them 

 after they have entered the trees. Observations have shown that 

 it is possible to kill the young of the former insect by making appli- 

 cations of oils or oily compounds to the bark shortly after the adults 

 have commenced operations, and there is a current belief to the 

 effect that such treatment may also be a valuable deterrent to 

 invasion. This has resulted in a number of preparations being placed 

 on the market and widely advertised as effective against these pests 

 and not injurious to the trees. There has been a natural tendency 

 to use -these compounds freely, and in some instances the outcome 

 has not been what was expected. The following observations are 

 placed on record for the purpose of showing the danger of the indis- 

 criminate use of oil preparations upon the bark of trees, since if 

 serious injury may develop within a few months upon young trees, 

 it is reasonable to expect that damage may result, even if long delayed, 

 in the case of those much larger. 



The material upon which the following observations are based is 

 an oily preparation which has been widely recommended under a 

 trade name. A sample of the compound was secured and through 

 the courtesy of the Honorable Edwin Duffey, State Commissioner 

 of Highways, was examined in the laboratory of that department. 

 The following is a transcript of the analysis: 



Per cent water present I .o 



Homogeneous Yes 



Specific gravity 1 .062 



Per cent free carbon 0.23 



Per cent distilling no° C.-170 C. (light oil) 4.3 



Per cent distilling 170 C.-235 C. (carbolic oils) 13.4 



Per cent distilling 235 C.-270 C. (creosote oil) 9.9 



Per cent distilling -. . 270 C.-300 C. (anthracene oils) 45.2 



Per cent pitch 27.2 



Specific gravity of total distillate 1 .022 



Bureau of tests, by J. E. Myers, chemist. 



Several red maple limbs with a diameter of approximately, ij 

 inches were cut March 2d, and after being rather thickly painted 

 with this preparation, were set with the cut ends in jars of water 

 to hinder evaporation so far as practical, and kept in a room at 

 ordinary indoor temperatures. Two days later some penetration 



