2i8 Report of the Department of Entomology of the 



pear and plum buds. Peacb buds were uninjiu'ed by the gas at 

 a strength of .22 gram, but showed indications of slight injury 

 at .3 gram. Experiments in the winter (December) resulted in 

 a failure to kill the scales with the gas at a strength less than 

 .3 gram, while the spring experiments (early June) resulted in 

 killing the scales with the gas at .18 gram. 



I. SPRAYING EXPERIMENTS WITH CRUDE PETROLEUM. 



INTRODUCTORY. 



Crude petroleum is one of the recent additions to the list of 

 insecticides. It was first brought into prominence in this capac- 

 ity by Dr. J. B. Smith^ of the New Jersey Agricultural Experi- 

 ment Station. During his experiments nearly 4,000 fruit trees 

 were treated, including the ordinary orchard fruits with the 

 exception of cherry. The petroleum was used pure and mixed 

 with 60 and 75 per ct. of water. The trees were treated at 

 various times from January to March. Summarizing these ex- 

 periments Dr. Smith states, in the bulletin previously referred 

 to, page 20: " Not a single case of injury to any tree treated in 

 winter has been observed; on the contrary in a number of cases 

 the oil seems to have acted as a stimulant, and the sprayed trees 

 have show'n greater vigor and better foliage than those 

 untreated." From his experiments Dr. Smith also draws the 

 conclusion (page 21) that crude petroleum " is harmless to the 

 most tender varieties and on the youngest trees." 



These experiments were followed in 1900 by a somewhat less 

 extensive series in West Virginia. In summing up the results, 

 Prof. L. C. Corbett, under whose direction the experiments were 

 made, states^ that apple, peach and plum trees sprayed May 16 

 seemed to thrive under a treatment of 20 per ct. crude petro- 

 leum. Also that none of the fruit or leaf buds were injured and 

 that although the trees were infested before treatment no live 

 scales were found on the treated trees. Experiments with undi- 

 luted crude petroleum applied April 3 to badly infested Japanese 



'N. .T. Agr. Exp. Sta. Bui. 138. 



'W. Va. Agr. Exp. Sta. Bui. 70. d. 37.*?. 



