REPORT OF THE DEPARTMENT OF ENTOMOLOGY. 415 
demonstrated that the insoluble portion possesses very weak, 
if any, insecticidal properties on this pest. The sulphur sprays 
derive their chief insecticidal value from the soluble lime- 
sulphur compounds. The addition of the sediment of a com- 
mercial or home-made lime-sulphur wash as extra material has 
apparently no detrimental influence on the effectiveness of the 
clear solution. The strength of the diluted preparation should 
be based on the clear solution. 
On the basis of reasonable efficiency and cost, the strengths 
of effective mixtures for the San José scale, using a lime- 
sulphur solution testing 33 degrees B., range from one gallon 
of the concentrate diluted with eight gallons of water to one 
gallon of the solution diluted with eleven gallons of water. In 
orchards where the scale is not thoroughly controlled, the 
stronger mixtures are recommended. For spraying for the 
blister-mite, a dilution of one gallon of the concentrate to 
eleven gallons of water makes an effective spray. 
Present evidence indicates that the common spraying arsen- 
icals do not materially affect the value of lime-sulphur mix- 
tures. In spraying for the scale or blister-mite, an arsenical 
in the usual amount for orchard treatment may apparently be 
safely added to a diluted sulphur solution for the purpose of 
controlling the bud-moth and casebearers, which are now very 
destructive in many apple orchards. 
The second year’s experiments with the home-made concen- 
trated lime-sulphur wash gave satisfactory results on the scale 
and blister-mite. The different preparations showed some 
variation in the density of the solution and in the quantity of 
sediment, requiring the use of a hydrometer to obtain diluted 
mixtures of definite strength. This method of preparing a sul- 
phur spray has several advantages, and should be tested by 
fruit growers owning suitable cooking outfits, to determine its 
applicability under their own conditions. The history of the 
commercial lime-sulphur mixtures indicates that the average 
fruit grower prefers to buy the prepared mixtures. 
