24 
that the maximum of egg hatching should occur twenty-nine days 
after the time when the greatest number of the preceding generation 
entered the bands. In the record made by Mr. Gibson it will be 
noted that the first maximum occurred June 26, and that by adding 
twenty-nine days we get the date of July 26. As the maximum of 
egg hatching extends over some time, spraying must be done before 
this date in order to get those which are early. In this instance the 
spraying should have been done between July 15 and August 4. 
Observation in the orchard in which the record was taken showed 
the period of greatest number of eggs to be between July 13 and 
~ August 4. 
The writer has never had an opportunity to test this ree ommenda- 
tion thoroughly. Many practical tests were made, and the results of 
these show that it is absolutely essential for highest efficiency to do 
the spraying when the largest number of larvee are entering. The 
writer would advise two thorough sprayings during this period. 
Another may be made if infestation is bad. 
MATERIAL FOR THE SPRAY. 
It is recommended in every case that arsenical sprays be used for 
this work. Paris green is most used in the proportions of 1 pound to 
160 gallons of water with 2 pounds of lime. By the use of this solu- 
tion excellent results are secured, but on account of its cost and liability 
to settle many are abandoning it for the white arsenic compounds. 
London purple is rarely used alone. Mr. Tiner, of Boise, and Olwell 
Brothers, of Centralpoint, Oreg., are using a combination of Paris 
green and London purple. Olwell Brothers use the following propor- 
tion: Water, 120 gallons; Paris green and London purple, 9 ounces 
each; and lime, 2 pounds. Mr. Tiner believes that in this way the 
poisons are kept in suspension better. Such good results are obtained 
that these growers are loth to adopt other compounds. White arsenic 
compounds are being used more and more with results just as good as 
those obtained with other arsenicals. Dr. H. P. Ustick, of Boise, and 
Mr. C. Hinze, of Payette, have used them successfully. Information 
as to the methods of making these sprays have been published in Idaho 
and the fruit growers are familiar with them. 
As far as the writer can learn, lead arsenate has never been used as a 
spray against this insect in the Pacific northwest. The writer believes 
that it will be found excellent, and will use it in experiments next 
season. There are a few fruit growers who use whale-oil soap with 
the sodium arsenite. Many observations were made in connection 
with the use of this mixture to ascertain if it caused the poison to 
remain on the fruit longer. Without doubt this is the case, but the 
soapy solution collects on the under sides of the apples and damages 
ead 
