14 
BULLETIN 116. 
The preparations were applied in the laboratory by means of an 
atomizer. An examination of the table shows that eggs and newly 
hatched larvae are easily killed even with the weakest strengths used. 
The point of difficulty is to secure a treatment which will penetrate the 
cottony masses. The experiments must be considered indicative at 
best, but they show that kerosene emulsion twenty per cent or more in 
strength, and fhe soaps at the rate of one pound to two gallons or 
stronger, will probably be effective. These insecticides cannot, of 
course, be used as a spray on the foliage. • It will be necessary to apply 
them by means of a sponge or brush. 
To Sum Up .—Summer treatments in practical experience have 
proved a disappointment, and must be considered a makeshift at best. 
If they become necessary, it will be better to combine two methods. 
As soon as the cottony masses appear, or certainly before the eggs have 
hatched in large numbers, trim out and promptly burn the infested 
twigs and such limbs as may be removed without seriously marring the 
appearance of the tree. The remaining masses should then be thorough¬ 
ly soaked with a strong kerosene emulsion or soap solution not less 
than one pound to two gallons in strength, the insecticides being ap¬ 
plied with a brush or sponge. 
Winter Treatment.—During 1903 and 1904 the writer conducted 
a series of experiments in the parks of Denver under the direction of 
Prof. Gillette, and with the consent and assistance of the park author¬ 
ities. Since these were published in detail with the Proceedings of the 
Association of Economic Entomologists (Bu. of Entom. Bui. 52) they 
will be but briefly reviewed here. 
Preliminary laboratory experiments conducted during January, 
1903, in which lime sulfur salt, kerosene emulsion, and hard whale oil 
soap were used showed little or no benefit from the first substance. 
Kerosene emulsion killed satisfactorily when twenty-five or more per 
cent in strength. The next application was twelve and one half per 
cent in strength and did not seem to be effective. Hard whale oil soap 
one pound to one gallon worked well, killing all exposed scales. The 
weaker strengths did not show an appreciable value. These experi¬ 
ments were repeated a week later, with practically the same results, 
except that the whale oil soap did not furnish such favorable data. 
The following winter two series of experiments were conducted in 
Curtis park, Denver. In the first, kerosene emulsion killed satisfactor¬ 
ily as low as twelve and one half per cent kerosene. Tobacco stem 
decoctions were entirely inefficient. Bowker’s tree soap at two pounds 
to one gallon shriveled the scales; at one pound to two gallons, killed 
two-thirds. Much to my regret, the test of one pound to one gallon 
was overlooked in checking up. This was unfortunate because this 
insecticide promised to be more useful than any of the so.aps previously 
used. 
In the second series, kerosene emulsion again killed as high as 
ninety-four per cent when, only twelve per cent kerosene in strength. 
Lime sulfur salt was again a total failure. Hard whale oil soap at one 
pound to one gallon killed ninety-eight per cent of the scales. 
As a result of this work kerosene emulsion, one-sixth kerosene, was 
