16 The Colorado Experiment Station. 
of the “Rex" to 10, and i to 11 gallons of water; Black Leaf tobac¬ 
co extract, four strengths, namely: i gallon to 30, 1 gallon to 40, 1 
gallon to 50, and 1 gallon to 70 gallons of water; Black Leaf “40,” 
(three strengths, namely: 1 gallon to 600, 1 gallon to 800, and 1 
gallon to 1,000 gallons of water; soluble oil, 1 strength, namely: 1 
gallon to 20 gallons of water. Thirty-eight trees in all were 
sprayed in this test, and 5 were left without any treatment, for 
checks. 
On the 8th of March, 21 trees were sprayed in Mr. M. Pax- 
son’s orchard at Clifton. These trees were five years of age, and 
fully as many eggs of the aphis, and larvae of the twig-borer were 
found on them as in the Strain orchard. The following insecti- 
sides were used on this date: Nico-fume at two strengths, namely, 
1 gallon of Nico-fume to 600, and 1 gallon to 800 gallons of water. 
Kerosene emulsion was applied at one strength only, namely, a 15 
per cent, oil emulsion prepared by using a common laundry soaD. 
Black Leaf was applied at one strength, namely, 1 gallon to 55 gal¬ 
lons of water. Home prepared lime and sulfur was applied at one 
strength, namely, 15 pounds of lime and 15 pounds of sulfur to 50 
gallons of water. This lime and sulfur was made in the ordinary 
way, and was boiled for one hour, so that a first class lime and sul¬ 
fur spray was prepared. 
On March 28th the peach buds were just showing their pink 
tips, and several sprays were again applied. At this time three of 
the tests were made with a mixed spray of arsenate of lead and one 
of the tobacco preparations, the arsenate of lead being used for the 
twig-borer, and the tobacco preparation with which it was mixed, 
for the aphis. The following insecticides were applied at this time 
to about 150 trees: Rex lime and sulfur, 1 gallon to 10 gallons of 
water; Black Leaf, 1 gallon to 50 gallons of water; Black Leaf, 1 
gallon to 70 gallons of water, combined with arsenate of lead 3 
pounds to 100 gallons of water; Black Leaf “40,” 1 gallon to 800 
gallons of water; Black Leaf “40,” 1 gallon to 1,000 gallons of 
water, combined with arsenate of lead 6 pounds to 100 gallons of 
water; Black Leaf “40,” 1 gallon to 900 gallons of water, com¬ 
bined with arsenate of lead 10 pounds to 100 gallons of water. 
Results of Experiments .—Table II gives the results of the first 
examination made on March 15, of trees sprayed in the Strain 
orchard. It may be seen from this table that all insecticides ap¬ 
plied on March 7th resulted in effective control, at all strengths. 
Subsequent examinations were made on March 24th, April 26th, 
and May nth, each one indicating practically the same results. It 
would seem from this experiment, that just as the eggs of this aphis 
are beginning to hatch is a favorable time to spray for its control. 
Lime and sulfur proved to be a perfect spray at this time. Appar- 
