14 
Not only do these experimental facts point to the inefficiency of 
Paris green as against the later broods of the codling moth, ‘but 
it is plain that the result was what we must have expected a 
prion. As the codling moth of all broods deposits the egg habit¬ 
ually on the blossom end of the apple, the poison taking effect 
only in case it reaches the surface of the apple between the calyx 
lobes, it is evident that there is little probability of effectively 
poisoning the fruit when the apple is full grown and pendent upon 
its stem. 
DANGER OF APPLICATION. 
Furthermore, I wish to emphasize especially the point that 
spraying after the apples have begun to hang downward is un¬ 
questionably dangerous , and should not be permitted under any 
circumstances if the fruit is afterwards to be used. The results 
ot the chemical analysis reported last year show that even heavy 
wind and violent rain are not sufficient to remove the poison 
from the fruit at this season; and remembering that the stem end 
of the apple presents a large conical pit by which the poison 
could be. received and held, where neither rain nor wind could 
dislodge it, we have additional reason for this absolute prohibition 
of the use of any poison dangerous to health, except when the 
fruit is young. 
COMPARISON OF PARIS GREEN AND OTHER POISONS. 
I made this year some further experiments, intended to test 
the relative efficacy of Paris green and a solution of arsenic* as 
applied to the codling moth, spraying two trees with the standard 
arsenic solution and two others with Paris green. The com¬ 
parative results are shown in Table IX., from which it will be 
seen at a glance that, so far as these experiments are concerned, 
the advantage remains decidedly with the Paris green.t The 
damage to apples treated with Paris green appears, in fact, to be only 
about forty-two per cent, of that following treatment with arsenic, 
—the ratio being not materially different for picked and fallen 
fruit. 
It will be remembered that I made a similar comparative experi¬ 
ment last year with Paris green and London purple, finding then, 
also, that the former poison was decidedly the more efficient. As 
only a single tree was treated with London purple, and as I seo 
no sufficient reason why this substance should not act as efficientiv 
as Paris green, I think that this result should not be insisted on. 
The facts, as made out, are given in Table X. 
The white arsenic, as analyzed for me in the University laboratory, proves to have been of 
excellent quality, containing ninety-eight per cent, of arsenious acid. 
tVe further noticed a decided scorching of the leaves on the trees which were sprayed with; 
arsenic, while those to which the Paris green was applied were entirely uninjured. 
