34 



height. The application was made between 2 and 3 p. m. on a bright, 

 dry day. At the same time a block of trees was sprayed with kero- 

 sene, or refined petroleum. The weather continued fair and dry for 

 four days, and there was no rainfall of any amount prior to April 11. 

 After the second day the kerosene had very largely evaporated, the 

 treated trees showing only a very light discoloration. Trees treated 

 with crude oil, on the other hand, were still very wet and oily looking. 

 The full-grown female scales of Diaspis pentagona were thoroughly 

 soaked and were permanently preserved, apparently, in the oil and had 

 scarcely changed color and were not drying up. After six days a 

 slight change in the coloration of the female scale insects began to be 

 observed, the color slightly altering from light lemon to light orange. 

 This change in coloration is a certain indication of the death and grad- 

 ual drying up of scale insects, which usuall}^ change from lemon to 

 orange and finally to brown or black in the different stages of drying 

 after being killed by an insecticide. Three weeks after the application 

 the trees treated with the crude oil were distinctly greasy in appear- 

 ance and blackened by the oil. Trees sprayed with the pure kerosene 

 gave no indication of having been treated at this time, the oil having 

 entirely evaporated. Curiously enough, the grass growing about the 

 trees treated with these oils seemed to be more affected by the refined 

 than the crude oil, being somewhat yellowed. This grass had been 

 sprayed pretty heavily with the oil to see what result would follow. 

 Two weeks later — namely, five weeks after the application — the bark 

 of the trees treated with the crude oil was still dark and distinctly oily. 

 All the trees treated with oil were leafing out and blooming just as 

 freely and fully as untreated trees. The grass, which had shown yel- 

 lowing at the outset, had entirely recovered and was apparently unin- 

 jured, seeming to indicate, at an} 7 rate, that grass will stand a consid- 

 erable application with both crude petroleum and the refined oil without 

 being killed. This fact is interesting in connection with the use of 

 this substance against white grubs on lawns. (See PI. I.) 



Lime, sulphur, and salt wash. — A mixture of this substance was 

 prepared, differing slightly from the formula given in Farmers' Bulle- 

 tin No. 19 in that the amount of lime was somewhat reduced, namely, 

 from 40 to 30 pounds. This reduction in the amount of lime was made 

 simpty because in the ordinary formula the lime is very greatly in 

 excess and remains as a pure lime sediment in the wash and has to he 

 kept in suspension by agitation. Even as thus reduced there is still a 

 considerable excess of lime. The formula followed was: 



Lime .pounds. . .30 



Sulphur do. ... 20 



Salt . do. ... 15 



Water .irallons. . 60 



The mixture was steam boiled altogether in barrels about four hours 

 and applied March 23 and repeated March 24. The hot liquid was 



