226 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
transferred to the cage, without disturbing them, if their cocoons have 
already been spun. Others can be readily removed from the trunk 
and be placed in the cages which have been provided with bark, chips 
and decaying bits of wood in which the larvae burrow and spin their co¬ 
coons. To determine development from some of the worms which 
have not suffered transferring, worm-infested apples are placed in the 
* 
cages; these apples are removed as soon as the worms have left the 
fruit. 
The cages are distributed throughout the Valley at different altitudes. 
Commercial apple orchards are found at heights ranging from 100 to 
nearly 2,000 feet. The average seasonal variations in the two extremes 
given, has been found to be from fifteen days to three weeks for the 
first brood and about ten days for the second. In the emergence of the 
first brood a very definite progression from the lower to the higher 
elevations occurs; it is much less pronounced for the second, due prob¬ 
ably to the fact that summer temperatures, during the day at least, 
are more nearly uniform throughout the Valley than are the spring 
temperatures. 
Table I—Maximum and Minimum Temperature Records for Years 1914-1917 Inclusive, Hood River, Oregon 
1914 
1915 
1916 
1917 
Max. 
Min. 
Max. 
Min. 
Max. 
Min. 
Max. 
Min. 
April. 
62 
53 
64 
39 
62 
39 
54 
36 
May. 
73 
58 
65 
42 
64 
41 
62 
43 
June. 
72 
50 
74 
49 
73 
46 
74 
48 
July. 
82 
53 
78 
56 
73 
50 
84 
52 
August. 
82 
52 
84 
54 
79 
52 
83 
52 
September. 
67 ' 
45 
72 
45 
72 
48 
As nearly normal orchard conditions as can be determined are taken 
into consideration when establishing the cages. This particularly 
refers to sun exposures, wind and rain, that emergence may be as nearly 
uniform to the surrounding orchard conditions as possible. As far as 
time has permitted, breeding cage observations and notes have been 
checked against field observations. 
The accompanying table (Table I) summarizes the different points 
of greatest interest in the life-history of the codling moth during the 
past four years. In comparing the dates of emergence of the moths of 
the first brood over this series of years there occurred a variation of a 
full month and a half. A record was not obtained in 1914 but in 1915 
the first moths issued in the cages on April 27. In 1916 this phenom¬ 
enon occurred on May 26 and in 1917 on June 15. The question that 
