CONTROL OF CODLING MOTH IN COLORADO. . 7 
In the treated plats over 90 per cent of the worms actually infesting 
the fruit gained entrance through the side of the apple and less than 
7 per cent entered by way of the calyx. In untreated plat X 72.31 
per cent of the larve entered through the side of the fruit and 26.45 
per cent through the calyx end. It will thus be seen from these data 
that one of the chief difficulties in controlling the codling moth in the 
Grand Valley of Colorado is to prevent the larve from entering the 
apple through the side. 
In the sik where arsenate of lead was employed the average 
number of larve for worm-infested fruit varied from 1.39 to 1.67, 
whereas in the arsenate of lime plats this average was increased to 
1.86 and 2, and in the unsprayed plat there was a further increase to 
2.08 larvee for each wormy apple. The higher the percentage of 
apples free from worms the lower the average number of worms per 
apple. Thus in plat III, where the best control was obtained and 
where 72.22 per cent of apples were free from worms, there was an 
average of only 0.39 larva per apple, and in plat X, which was un- 
sprayed and yielded but 13.51 per cent of worm-free eat, there were 
1.80 larvee per apple. 
In scoring results, account was taken of the so-called codling 
moth ‘“‘sting’’ (PI. ID). The sting is a shallow excavation extending 
through the skin of the apple into the flesh to a depth of about one- 
sixteenth to three thirty-seconds of an inch. It is caused by newly 
hatched larve that only succeed in eating their way through the 
skin before succumbing to the poison, or, for other reasons, do not 
penetrate deeper into the fruit. In the sprayed plats the average 
number of stings per apple varied from 0.82 to 1.91, whereas in the 
unsprayed plat the average was only 0.12. 
It is the belief of the writers that, with a uniform infestation and 
crop and with other factors equal, the number of stings is directly 
proportional to the number of worm-free apples. In other words, 
if the spray treatment is effective, the only indication of worm attack 
will be found in the sting marks, and these will increase within 
certain limits as the number of worm-free apples increases. In the 
case of unsprayed fruit, the worms are not subjected to a poison, 
and hence what might result in only a sting in a sprayed apple 
becomes a worm hole in the untreated fruit. It should not be 
inferred, however, that unsprayed fruit is totally devoid of stings, 
for sting marks sometimes occur on untreated fruit and may be 
accounted for by larvee which start an entrance hole and then change 
to another place, or by larve that, before penetrating very far into 
the fruit, are blown off by wind, brushed off by foliage, or washed off 
by heavy rains. 
SPRAYING EXPERIMENTS IN 1916. 
In 1916 the Gus J. Johnson orchard, at Highland Park, and the 
J. D. Nettleton orchard, at Fruitvale, were used for experimental 
purposes. 
