CODLING MOTH IN CENTRAL APPALACHIAN REGION. 45 



SEASONAL EFFECT OF WEATHER CONDITIONS ON THE DIFFERENT 

 STAGES OF THE CODLING MOTH. 



The beginning of emergence of the spring-brood codling moths 

 | varies greatly from season to season, depending in any given year 

 upon the temperature conditions that prevail during March, April, 

 and May. 



It will be noted, however, that in spite of the wide variation in the 

 thne of emergence of the spring-brood moths in 1912 and 1913 there 

 was a tendency for the later stages of the insect to appear at more 

 nearly the same periods both years. This is probably due to an 

 equalization of midsummer weather conditions subjecting the later 

 stages of the insect to the influences of a more constant seasonal 

 temperature factor. At Winchester, where the codling moth was 

 under closer observation than at other points, we find that while 

 spring-brood moths emerged at least 10 days later in 1912 than in 

 1913, the second-brood larvae began entering the fruit at practically 

 the same time both years. 



Hammar, 1 in his report on the codling moth in Pennsylvania, gives 

 the following in his general summary: 



The time of the emergence of the spring brood of the moths is variable under differ- 

 ent seasonal conditions and depends largely upon the relative lateness of the spring. 



The time of emergence of the summer brood, or first brood, of moths is fairly constant 

 and generally commences about the 1st of August. 



From the results of the band records and rearing work of 1912 and 

 1913 it v^ould seem, therefore, that in all except very unusual seasons 

 we may expect the feeding of second-brood larvae to begin in the 

 different sections about as follows: Charlottesville, Va., July 1; 

 Fishersville, Va., July 10; Winchester, Va., July 15; Hagerstown, 

 Md., July 25. 



CANNIBALISM AMONG CODLING-MOTH LARV^. 



During the progress of these studies it was noticed frequently that 

 when a collection of codling-moth larvae was confined in a rearing jar 

 a considerable loss in their numbers from cannibalism was likely to 

 occur. This habit, of the stronger larvae devouring their weaker 

 fellows, has been commented on by Hammar. 2 He states that can- 

 nib alism among the larvae probably takes place also under normal 

 conditions. In the jars the loss from this cause during the present 

 investigations was frequently sufficient to amount to a considerable 

 factor in influencing the number of moths to appear later. 



1 Hammar, A. G. The codling moth in northwestern Pennsylvania. U. S. Dept. Agr., Bur. Ent., Bui. 

 80, Pt. VI, p. Ill, 1910. 



2 Hammar, A. G. Life-history studies on the codling moth in Michigan. U. S. Dept. Agr., Bur. Ent., 

 Bui. 115, Pt. I, p. 1-86, 1912. See p. 83. 



