256 Report of the Department of Entomology of the 



SERIES II. SPRAYING EXPERIMENTS TO DETERMINE 



THE EFFECTS OF CRUDE PETROLEUM UPON 



HIBERNATING SCALES. 



The experiments of this series were conducted in Orchards 

 II, III and IV. 



orchard II : PEARS. 



The experiments of Series II were begun in this orchard 

 which consists of 101 pear trees, nearly all of which are standard 

 Rartletts. The trees were planted about six years ago and 

 except for the first two years have received but little care. 

 During the past four years the orchard has been in sod. It is 

 quite probable that some of the trees were infested when 

 planted but the scale was not noticed until the spring of 1898. 

 ^Yhen the experiments were begun in 1900 most of the trees 

 were extensively infested, many being encrusted on the trunk 

 and larger limbs. Before the experiments were begun they 

 were carefully trimmed and the orchard was divided into two 

 sections. The first, containing 54 trees, was treated with crude 

 petroleum, and the second, containing all of the remaining trees, 

 except a few reserved for checks, with hydrocyanic acid gas as 

 noted in a subsequent section of this bulletin. 



Summaries of the spraying experiments and results in this 

 orchard are given in Tables IV, V, VI and VII. The check 

 trees are not recorded in the tables. In every case the scales 

 had multiplied rapidly. The live ones were abundant upon both 

 the new and old growth. 



