109 
Effects of Experimental, Summer Spray. 
Treatment 
No. of 
trees 
Leaves 
ex- 
amined 
Scales 
ex- 
amined 
Insecticide 
Part of 
hatching 
period 
killed 
by spray 
10 per cent. Kerosene 
Beginning 
1 
75 
48,789 
3.3 
10 per cent. Kerosene 
Middle 
1 
50 
19,425 
64 
10 per cent. Kerosene. 
End 
3 
150 
281,271 
68 
10 per cent. Kerosene 
Middle 
and end 
1 
100 
57,179 
82 
] lb. Whale-oil Soap to 
6 gal. water 
End 
1 
75 
77,171 
43 
From this it will be seen that 75 leaves bearing 49,000 scales 
were examined from the tree sprayed July 3, and that only 33 per 
cent, of the scales on this tree had been killed. In this case a first 
inspection was made ten days after the spray was applied, and a 
second, seven days later. The trees sprayed once July 11 — at the 
middle of the hatching period — and from which 50 leaves bearing 
19,000 scales were examined, showed a ratio of benefit of 64 per cent. ; 
that is, 64 per cent, of the scales alive when the spray was applied, 
were dead a few hours later. In other words, by postponing the 
treatment from the 3d to the nth of the month the effect of it had 
been nearly doubled. A similar but somewhat greater effect was 
produced by single treatments given July 19 and 20, when the 
greater part of the eggs were already hatched, 68 per cent, of the liv- 
ing scales among the 281,000 borne by the 150 leaves examined being 
thus killed. The most effective treatment was a double spraying, 
one application at the middle and the other about the end of the 
hatching period, which, as shown by an examination of 57,000 scales 
from 100 leaves of the tree so treated, killed 82 per cent, of the 
scales alive when the tree was sprayed. That is, the effect of the 
operation had been increased approximately 28 per cent, by the sec- 
ond spraying. 
A comparison of the scales on the two surfaces of the leaves 
showed that the ratio of those killed on the lower surface was only 
72 per cent, that of those killed on the upper surface. This was doubt- 
