56 BULLETIN 1235, U. S. DEPARTMENT OP AGRICULTURE. 



every three days during the time the spring brood of moths were 

 emerging. These cages were stocked with larvae in the fall, the larvae 

 being allowed to spin cocoons under a burlap band around a section 

 of a tree limb held upright in the center of the cage. The cages were 

 placed in the crotches of trees in orchards early in March, before any 

 development had taken place. They were thus kept under as nearly 

 normal conditions as possible. The elevation at these stations ranged 

 from 800 to 2,000 feet. These cages differed very little in the time 

 of emergence of moths. At most of the stations the maximum emer- 

 gence occurred within three days of the maximum date at the in- 

 sectary at Yakima. Thus in 1920 the maximum date at Yakima 

 was June 2. Of 13 cages, the maximum emergence occurred in 10 

 of them during the period from June 1 to June 4, inclusive. Of the 

 other three cages, one was in the lower valley on a south slope, and 

 the maximum occurred May 21, and the other two were at elevations 

 600 and 1,000 feet higher than Yakima, and the maximum emer- 

 gence occurred on June 8 and June 15, respectively. In 1921 the 

 maximum emergence at the insectary and in a cage in the experi- 

 mental orchard occurred on May 30. In the other nine cages it 

 occurred from three to nine days later. In 1922 maximum emer- 

 gence of moths again occurred at most stations within a few days of 

 the maximum at the insectary at Yakima. The maximum at Yakima 

 was on June 1. In the lower valley two stations were maintained 

 and the maximum occurred at one of them on May 27, and at the 

 other on May 30. In the upper valley the maximum at two stations 

 was May 30; at five, June 2; and at one, with an elevation of 2,000 

 feet, June 8. This evidence tends to "show that there is not very 

 much difference between different parts of the two valleys in the 

 time of emergence of moths of the spring brood, though, owing to the 

 warmer summer weather in the lower valley, the majority of the first 

 brood of larvae became full-grown from a week to two weeks earlier 

 than in the upper valley. 



SEASONAL-HISTORY STUDIES AT WENATCHEE, WASH., 1915 AND 



1916. 



During the seasons of 1915 and 1916 the senior author, while sta- 

 tioned in the Wenatchee Valley of Washington, undertook some life- 

 history studies of the codling moth. Since these were carried on as 

 a minor project, it was not possible to make as detailed studies as 

 have been made at Yakima, but it is deemed advisable to present 

 here a summary of the data that were obtained in order that a com- 

 parison may be drawn between the two districts. 



The Wenatchee Valley is situated in central Washington, about 

 60 miles north of Yakima. The elevation at Wenatchee, which is 

 just south of the confluence of the Wenatchee and Columbia Rivers, 

 is only about 800 feet, but as the valley is nearer the Cascade Moun- 

 tains than the Yakima Valley the season is about the same. The 

 average apple crop in the Wenatchee district is about the same as 

 that of the Yakima district. 



The winter of 1914-15 was mild and the spring early. Maximum 

 temperatures of 80° F. or more were experienced on April 16 to 19, 

 inclusive, which is unusual for this month. Warm weather was again 

 experienced during the first week in May, after which temperatures 



