CODLING MOTH IN COLORADO. 115 



SUMMARY. 



The life-history studies recorded herein were made in the Grand 

 Valley of Colorado during the seasons of 1915 and 1916. 



The climate of the Grand Valley is comparatively dry and warm 

 during the summer season, and is very favorable to the development 

 of the codling moth. 



According to the data secured in these studies, there are two com- 

 plete generations and a partial third generation of the codling moth 

 in the Grand Valley. 



Length of the pupal stage of the spring brood. — In 1915 the length 

 of the pupal stage of the spring brood averaged 27.58 days, the maxi- 

 mum was 34 days, and the minimum 15. In 1916 the average was 

 26.80 days, the maximum 36, and the minimum 13. 



Oviposition by moths of the spring brood. — In 1915 the average 

 number of days before oviposition was 6.19, the maximum 19, and 

 the minimum 2; the average number of days for the period of ovi- 

 position was 13.82, the maximum 33, and the minimum 1 ; the average 

 number of days from the date of emergence to the date of last ovi- 

 position was 19.14, the maximum 37, and the minimum 5. In 1916 

 the average number of days before oviposition was 6.07, the maxi- 

 mum 13, and the minimum 2 ; the average number of days for the 

 period of oviposition was 13.38, the maximum 32, and the minimum 

 1; the average number of days from the date of emergence to the 

 last oviposition was 18.46, the maximum 34, and the minimum 7. 



Number of eggs per female moth of the spring brood. — Accord- 

 ing to the oviposition studies of the spring-brood moths of 1915, 

 the average number of eggs per female moth was 12.59 ; in 1916, 11.34 

 eggs. 



Length of life of moths of the spring brood. — In 1915 the average 

 length of life of the male moths was 14.59 days and of the female 

 moths 15.86 days; the maximum length of life of the male moths 

 was 36 days and of the female moths 39 days ; the minimum length 

 of life of the male moths was 1 day and of the female moths 1 day. 

 In 1916 the average length of life of the male moths was 14.67 days 

 and of the female moths 15.73 days; the maximum length of life 

 of the male moths was 35 days and of the female moths 39 days : the 

 minimum length of life of the male moths was 1 day and of the 

 female moths 1 day. 



THE FIRST GENERATION. 



Embryological changes and length of the incubation period of 

 first-brood eggs. — The embryological changes in the eggs of the 

 first brood and the length of the incubation period were as follows : 

 In 1915 the average number of days from the date of egg deposition 



