52 



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 : 



1. Pewaukee (always badly infested). 6. Wealthy (very variable). 



2. Spitzenberg. 7. Ben Davis (very variable). 



3. Bell-flower. 8. Borne 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 



