28 THE HOP APHIS IN THE PACIFIC REGION. 
ADVANTAGES OF FLOUR PASTE OVER WHALE-OIL SOAP AS A SPREADER 
FOR CONTACT INSECTICIDES. 
Flour paste costs 8.8 cents per 100 gallons of spray. Cheap flour 
is always available, and the paste has no odor. Whale-oil soap costs 
20 cents per 100 gallons of spray , is not always available, and has 
a disagreeable odor. 
Both materials have to be heated before using. 
The neutrality of flour paste was proven by the fact that when 
applied upon the foliage and blossoms of the hop, in proportions as 
high as 12 gallons of paste to 100 gallons of spray, no injurious 
effects resulted. When sprayed upon the hop burrs and delicate hop 
cones, it did not prevent pollination or injure the appearance of the 
scales. 
QUASSIA. 
Quassia is the extract from the wood of Picrsena excelsa, a tree 
occurring in Jamaica and containing the alkaloid quassin (C 32 H 42 O 10 ) 
in the form of crystalline rectangular plates. Quassia chips contain 
no tannic acid. 
EFFECT OF QUASSIA ON APHIDES. 
A solution of quassia containing the extract from 5.33 ounces of 
quassia chips in 1 quart of water was diluted one-half and sprayed 
on Ilyalopterus pruni on prune. It was found necessary to wash 
the waxy pulverulence from the insects before they could be wetted. 
The leaves were tagged with the numbers of aphides present and the 
twigs set into water in the laboratory. A check branch was sprayed 
with pure water. That the strong quassia solutions have a decided 
insecticidal value is shown by the following data: 
Aphides present before spraying, 37, 40, 109, 92, 190, 75, 140, 40; total, 723. 
Aphides present after spraying, 0, 30, 3, 1, 0, 25, 0, 0; total, 59. 
Per cent killed, 92. 
Quassia solution at the rate of 7 pounds of chips to 250 gallons of 
water was applied to the aphides with the following results: 
Aphides present before spraying, 48, 60, 30, 40, 73, 30, 200, 100, 63, 128, 12; total, 784. 
Aphides present after spraying, 0, 0, 5, 0, 0, 0, 1, 2, 7, 9, 10; total, 34. 
Per cent killed, 96. 
The aphides on sprayed leaves turned brown when dead. The 
check leaves contained living insects only. 
