13 
sible variations of this sort are so numerous, and a precise exam¬ 
ination of their effects upon the remedy would require such an 
interminable series of laborious and costly experiments, that I 
have thought it best to leave this subject to the practical fruit 
grower, for determination on the larger scale of orchard practice. 
It is also especially to be noted that the final summaries of in¬ 
jury are much greater in our experiments than they would have 
been if all the trees in the orchard had been treated, as m the 
practical application of this method in the field, Since we pui- 
posely left as many trees untouched as we sprayed, and since in 
our experiments of this year the trees under observation were 
surrounded by other trees heavily laden with apples, to which v> e 
gave no attention, there were necessarily bred in these trees an 
abundance of codling moths of the first brood, which, spreading to 
our experimental trees, must have greatly increased the latio of 
injury by the later broods. 
In orchard use, however, where all the trees would be poisoned, 
the later broods could represent only the small percentage of the 
last generation which had escaped the treatment. 
TIME OF APPLICATION. 
We have next to determine the time of the year at which poi¬ 
soning is the most effective; whether, in fact, it takes principal 
-effect upon the first brood or the later ones. A moment’s reflection 
will show that if only the first brood of the larvae was directly 
diminished in a certain ratio, the second brood should show a 
similarly diminished ratio, since these descend from the first, 
whereas if both first and second broods are directly poisoned, then 
the ratio of damage to the second brood should be greatei than 
that to the first; or, in other words, the percentage of benefit to 
the picked apples should be greater than that to the fallen. Om 
data for the present season do not apply to this question, since 
all the sprayings were made in May and early in June, while the 
apples were still very small; and it is incredible that the poison 
should have remained upon the fruit through all the \icissitudes 
of weather and time for the two months and more that elapsed 
before the appearance of the second brood of larvae. The results 
of last year, however, when the spraying was continued until Sep¬ 
tember 3, give us important information. Referring to I able 1., 
it will be seen that the benefit to the picked apples instead ot 
being greater than that to the fallen fruit was last year about 
twenty-seven per cent, less, so that certainly no appreciable e ec 
was produced by spraying during the life of the second brood. 
The greater injury to the picked fruit is readily accounted ioi b} 
a circumstance to which I have already alluded; \ix.,. that our ex¬ 
perimental trees were surrounded by others upon which no exper¬ 
iment w r as tried, and were consequently subject to invasion by 
codling moths of the second brood, reared upon these unpoisoned 
trees. 
