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INTRODUCTION AND SPREAD. 
Previous to 1887 the codling moth was practically unknown in Idaho. 
It was probably present before that time, but did so little damage as 
not to be noticed. 
The moth, without doubt, came into the northern part by way of 
the Snake River valley. Its spread was rapid, although checked to 
some extent by the long distance between orchards. 
The sections which are shipping apples are now all infested. The 
newer orchards are more or less free, but can not remain so very long. 
RESISTANCE OF VARIETIES OF APPLES. 
Only scattered observations were made upon this point, and these . 
do not harmonize. Some of the varieties in order of damage sustained 
are: 
5. Wealthy (very variable). 
. Ben Davis (very variable). 
1. Pewaukee (always badly infested). 
2. Spitzenberg. 
bo f 
3. Bell-flower. 8. Rome Beauty (very variable). 
4, King. 9. Winesap (but little infested). 
5. Gravenstein. 
This question is believed to be one of the most important to be 
worked out, as in general the apples given as least infested are the 
best varieties for Idaho. 
LIFE HISTORY OF THE CODLING MOTH. 
The life history, as usually given, applies to the insect in a climate 
far different from that of Idaho. On this account I spent much time 
in studying the variations in the life history. 
THE EGG. 
The eggs can be found at any time during the summer, either upon 
the fruit or upon the upper surface of the leaves. In certain orchards 
the eggs were almost entirely upon the fruits; in orchards near by 
they were nearly all upon the leaves. Where apples were in abun- 
dance there were but few eggs upon the leaves, and where apples were 
scarce but few eggs were upon them. Apparently the moth prefers 
to lay its eggs upon the fruits. 
The eggs have been described as whitish, milk-like spots. They 
adhere closely to the fruit or leaf, and even after hatching the shells 
remain for a long time. When the egg is a few days old a brown 
horseshoe-shaped band appears indicating the embryonic larva. 
THE LARVA. 
In from about six to eight days the larva is fully formed and breaks 
its way out of the shell. Most of them come out through the top 
