THE CODLING MOTH IN MICHIGAN. 



73 



logical developments. In the course of the emergence period 

 part of the moths of the spring brood were hampered by cold rams, 

 which set in during the middle of June and caused a somewhat pro- 

 .longed delay for about one-half of the moths. This irregularity in 

 the development of the insect produced an unusual effect upon the 

 time and rate of occurrence of the separate stages for the rest of 

 the season. This is noticeable from a study of the curves of figure 

 21 for 1911. In the summer brood there occurred an abundance 

 of moths at the very start of the emergence, which was followed 

 by a decrease in number as a result of the delay found in the spring 

 brood; then again an abundance of moths appeared during the first 

 half of August as a result of the emergence of the later half of the 

 spring brood of moths. The prevailing high temperature advanced 

 the earliest developing insects to the extent that the second-brood 

 larvae appeared three weeks ahead of those of 1910, and further 

 prolonged to a very unusual extent the time of emergence of the 

 summer moths, the period of egg deposition, and the period of 

 hatching of the second brood of larva; . The large fruit crop, together 

 with the high temperature, favored the development of a large 

 second brood of larvae. For the total number of larvae collected at 

 the Douglas band records 50.5 per cent were of the first brood and 

 49.5 per cent of the second brood. 



Table LXXI. — Summary of results of band records for 1909, 1910, and 1911, at Douglas, 



Mich. 



Observations. 



Percentages for— 



1909 1910 1911 



Moths emerging the same season 



Moths emerging the following season 



Total emergence of moths 



Wintering larvae of total band collection. . 



Wintering larvae killed by frost 



Parasitized larvae 



Relative proportion of first-brood larvae... 

 Relative proportion of second-brood larvae 



Transforming larvae of first brood 



Wintering larvae of first brood 



50.5 

 49.5 

 34.9 

 65.1 



The results from the band records for the three years at Douglas 

 show that of the first-brood larvae about one-third transformed 

 the same season and two-thirds passed the winter in the larval stage, 

 as do all second-brood larvae. (See Table LXXI.) 



INSECT ENEMIES. 1 



PREDACEOUS INSECTS. 



Several predaceous insects have been found to attack the larvae 

 and pupae of the codling moth. Of these a small black beetle and its 

 larva, Tenebroides corticalis Melsh. (PL III, figs. 4, 5), belonging to 



1 For information relative to the bird enemies of the codling moth, see Yearbook of the Department 

 of Agriculture for 1911, pp. 199-208, "Bird Enemies of the Codling Moth," by W. L. McAtee. 



