658 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
When tobacco dust is added to lime-sulfur some hydrogen-sulfide may 
be liberated. This difficulty can be partially overcome by the addition 
of a few pounds of hydrated lime per 100 gallons of spray mixture. No 
test for H 2 S was obtained when the filtrate from experiment No. 9 was 
added to lime-sulfur solution. 
From a theoretical standpoint nicotine .should be readily volatilized 
from alkaline lime-sulfur solution. A few preliminary experiments on 
the volatility of nicotine from this mixed spray have been made. These 
experiments indicate that the rate of volatility is about the same as that 
from other preparations of the same nicotine content. 
The chemical compatability of this triple spray is discussed in Bul¬ 
letin No. 521 of this station. 2 
THE EFFECTS OF OIL SPRAY ON APPLE APHIDS 
By K. C. Sullivan and O. C. McBride 
In certain sections of the Mississippi Valley the lubricating oil emul¬ 
sions have been used as a dormant spray for the control of San Jose 
Scale with a certain degree of success. The question has been raised as 
to the effect of these emulsions on apple aphids. The common practice 
is to apply a separate spray of nicotine sulphate just as soon as the 
aphids hatch. This extra spray costs considerable in both time and 
material. Some growers however, have added the nicotine sulphate to 
the first summer spray of lime sulphur and arsenate of lead. This has 
been fairly satisfactory but is just a little late for the most effective results. 
The lubricating oil emulsions have been used extensively at the Mis¬ 
souri Agricultural Experiment Station during the past two years in 
order to determine their value as a dormant spray and also as a summer 
spray on apple trees. During the course of this work extensive observa¬ 
tions were made as to the efficiency of these sprays in controlling apple 
aphids. 
The aphis which has caused the most trouble in Missouri on apples 
during the past two years is the common grain aphis (Siphocoryne 
avenae Fab.) This aphis migrates to the apple in the fall from the grain 
and deposits eggs on the small twigs and buds. At the time the buds 
begin to push out in the spring the eggs hatch. From three to four gen¬ 
erations are reared on the apple before they migrate back to the grain. 
They are often present in large numbers and cause considerable damage 
to the young tender growth. 
2 Thatcher, R. W., and Streeter, Leon R. Chemical Studies of the Combined Lead 
Arsenate and Lime-Sulfur Spray. N. Y. S. Agr. Exp. Sta. Bui. No. 521. 1924. 
