334 REpoRtT OF THE DEPARTMENT OF ENTOMOLOGY OF THE 
Any one who has had occasion to examine into the condition 
of a large number of scales appreciates the losses in numbers 
through this source alone. This is a point well worth bearing 
in mind if a statistical determination during the dormant period 
of the scale is to be the criterion of the efficiency of washes just 
previously applied rather than the condition of these same trees 
at the close of the following breeding season of the scale. For 
this reason the season was chosen when the larve were most 
active, the white and black scales numerous, and there was evi- 
dence of living adult scales. That each experiment might con- 
tain scales of an average condition the apples were divided into 
lots of from 3 to 20 each. 
The experiments furnish valuable data upon the insecticidal 
properties of the wash in showing that, upon application, the 
soluble ingredients cause the death of all the scales with which 
they come in contact, and that when the wash has dried there 
still remain soluble ingredients destructive to scale life, the 
duration of the insecticidal properties of which is largely deter- 
mined by the degrees of heat and moisture immediately follow- 
ing the application. 
Experiment I, second series, shows unmistakably marked in- 
secticidal properties in the wash three days after its application, 
and to a much less extent on the fourth. In Experiment II it 
is shown that one good drenching of the wash as by a heavy 
rain, following an application, causes a wasteful and excessive 
leaching away of these desirable compounds, and that the length 
of time that these are retained in the wash is dependent upon 
the number and degree of subsequent drenchings. In Experi- 
ment V there is strong evidence that conditions of heat affect the 
wash also, higher temperatures assisting in the breaking down 
of the soluble ingredients to less efficient ones, and lower tem- 
peratures retarding such action, thus extending the time in 
which these ingredients can act as efficient insecticides. 
Attention is also directed to the results with the insoluble or 
slowly soluble ingredients that formed a crust when dry over the 
surface of the fruit. It was apparent that the effect of these 
insoluble ingredients was largely mechanical in that the young 
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