318 Report OF THE DEPARTMENT OF ENTOMOLOGY OF THE 
Apple No. 15.— Fourteen adult females alive with from 8 to 12 
living and 8 to 6 dead larve beneath their scales; 11 adult 
females dead with no young; 14 young just forming scales 
(white stage) slightly covered with wash, alive; 39 scales, black 
stage, alive. Remaining scales dead. 
CONCLUSIONS. 
For this series of experiments the wash that had been allowed 
to dry for 24 hours on the glass plate was sprayed with water 
every day for six days. Each day the residue thus obtained was. 
sprayed upon an infested apple (Nos. 8-13). The results are 
very pronounced. The residue obtained from the first applica- 
tion of the water to the dried wash, killed all of the scales or 
100 per ct. This residue undoubtedly contained much of the 
soluble ingredients as well as a small amount of the insoluble 
or Slowly soluble ingredients which formed a crust on the apple. 
As was to be expected, the products of the succeeding applica- 
tions of water to the wash on the glass plate were much weaker 
in soluble ingredients and had correspondingly less effect upon 
the scale as shown by the percentage killed on apples 10 to 13. 
The same result is shown on apple 14. When more of the pre- 
cipitate was obtained, as was the case for apple 15, fewer young 
were produced and more of the scales were killed. 
While it is difficult to determine the exact effect of the soluble 
ingredients and heavy precipitates of the wash, as it was im- 
possible to know in all cases the exact condition of the scales 
on the treated apples, the above table and results give further 
evidence that the soluble ingredients act as a direct contact 
poison, killing the adults and young, while the insoluble or 
slowly soluble compounds act indirectly as a mechanical barrier 
to the development of the young scales. 
EXPERIMENT III. 
This experiment was principally for the purpose of deter- 
mining the effect of an excessive amount of precipitates (or 
insoluble or slowly soluble ingredients of the wash) upon the 
scale. This has a bearing upon the relative value of a large or 
small excess of lime in the wash, 
a 
