THE CODLING MOTH IN MICHIGAN. 47 



Within a week of the maturity of the larvae the bagged fruit was 

 removed from the trees and placed in cages. The average length of 

 feeding of larva? in bagged fruit was 20.96 days against 21.43 days for 

 those reared in fruit in the cages, being a difference of less than 

 half a day. 



Time of maturity of larvse. — From the band records the time of 

 maturity and the relative abundance of full-grown larvse are deter- 

 mined for field conditions. The Douglas band records (fig. 18) have 

 been taken as typical and represent also the surrounding sections of 

 the station. The first larvae were collected June 25 and subsequently 

 in abundance throughout the season. It is estimated that the last 

 larvae of the first brood appeared September 10. 1 



Percentage of transforming and wintering larvse. — Table LXVIII 

 shows that 40 per cent of the first-brood larvae transformed and 60 

 per cent wintered as larvae. The observations are from five sepa- 

 rate band records. 



Larval life in the cocoon. — The larval life in the cocoon is here 

 broadly considered to be the time necessary for the making of the 

 cocoons, and is recorded from the time the larvae leave the fruit to 

 the time of pupation. More closely considered, this period actually 

 includes the time the larva searches for its hiding place and the pre- 

 pupal stage, when the larva remains inactive and undergoes struc- 

 tural changes previous to transformation. The wintering larvae of 

 the first brood are not included here, as these remain in the larval 

 stage until the following spring. The results of 132 observations 

 (Table XL VIII) show a variation of 2 to 18 days and an average of 

 7.2 days. The data for the extremely short periods of making of 

 cocoons are somewhat misleading in that certain larvae in the act of 

 making the cocoons have been disturbed by others and have then 

 abandoned the first cocoon and made a new one. The records of 

 Table XL VIII in such instances only show the time for the making 

 of the last cocoon. The prolonged period of time as found in some 

 cases is probably due to a diseased condition of these larvae. 



i For methods of determining the time of appearance of the last larvae of the first brood and the first 

 larvse of the second brood see page 15. 



