458 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 13 
The coefficient, now obtained by dividing the percentage of worms 
by the percentage of stings, gives a different interpretation to these 
figures, and shows that the best results were obtained by the rod on 
those apples growing not higher than twelve feet from the ground. 
No. Treatment 
Total 
Total 
Per cent 
Ratio 
worms to 
worms 
stings 
wormy 
stings 
16. LdAs, 1/50; 5 applications, rod. . 
873 
2,643 
5.36 
.33 
17. Same. 
667 
1,954 
17.15 
.34 
18. Same, gun. 
915 
1,726 
4.42 
.53 
Illustrations 16-18 were taken from 
Mr. Newcomer’s 
results in 
our last year’s cooperative spraying experiments at Yakima. The 
trees of 16 and 17 were in the same plot, but those of number 17 were 
adjacent to the block of unsprayed checks; the others were removed 
by several rows of sprayed trees. Although receiving identical treat¬ 
ment the trees of example 17 showed over three times as many worms 
as those of 16, but the index number remains the same. In terms 
of worm-free fruit the gun-sprayed trees excel; the index number, 
however, shows again that comparative excellence is an illusion and 
resulted from fewer larvae hatching on those trees. 
These citations illustrate that the ratio of worms to stings affords a 
more dependable index of the value of codling moth treatment than 
the customary percentage of final worminess. How far its applica¬ 
tion will extend will probably be brought speedily to light by investi¬ 
gators stationed over the country. It is applicable for cover sprays 
and sprayings. The calyx spray must be measured otherwise, for a 
proper calyx spray leaves no calyx stings. As codling larvae some¬ 
times nibble here and there, the number of stings is not an absolute 
indication of the number of poisoned worms. The effect of repellent 
additions to the spray, or of thickened apple skin in causing the larva 
to spew out its nibblings, may interfere with the validity of the index 
number, and the range of such effects should be investigated. 
Despite some shortcomings, the coefficient method affords a means 
for interpreting codling moth treatments from a new angle. No 
matter how many worms attack a tree, how abundant or shy the crop, 
whether one or one thousand trees are sprayed, where the trees are 
located, or how many apples are finally examined, the ratio of unpoi¬ 
soned to poisoned worms should be an approximately constant guide 
for evaluating each treatment. 
Chairman A. L. Melander: We shall now have the pleasure of 
an address by M. L. Dean, of the Washington State Department of 
Horticulture, relative to the work of pest control. 
