248 REPORT OF THE DEPARTMENT OF ENTOMOLOGY OF THE 
pear and plum buds. Peach buds were uninjured 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 
.8 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 shown 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. J. Agr. Exp. Sta. Bul. 138. 
"W. Va. Agr. Exp. Sta. Bul. 70, p. 373. 
