CODLING MOTH IN COLORADO. 



11 



pupation of 320 larvae are given in Table III and illustrated in 

 figure 1. 



It will be noted that the earliest pupation occurred April 14, when 

 two larvae transformed, and that the last of the wintering larvae 

 pupated June 8 or approximately 8 weeks later. On April 26 there 

 was a marked increase in the rate of pupation and a still greater 

 increase two days later, owing to 

 higher temperatures, as shown in 

 figure 1. Following this activity 

 the temperatures became abnor- 

 mally low, reaching in the insect- 

 ary a minimum of 27° F. on May 

 2, on this date only one larva 

 pupating. This freeze contributed 

 largely to the destruction of prac- 

 tically the entire fruit crop of the 

 Grand Valley west of the Pali- 

 sade district. Freezing tempera- 

 tures recurred on the mornings of 

 May 3, 4, and 7, but on the latter date the temperature reached a 

 maximum of 70° F., and, as a result, 18 larvae pupated. Pupation 

 thereafter continued quite regularly (except on May 10) and reached 

 its maximum on May 12. During the period of one week, May 7 

 to 13, inclusive, approximately 40 per cent of the wintering larvae 

 pupated. Following this crest of activity the rate of pupation gradu- 

 ally diminished in the normal way. 



Fig. 1. — Time of pupation of spring- 

 brood pupae of the codling moth,. Grand 

 Junction, Colo., 1915. 



Table III. — Time of pupation of wintering larva? of the codUng moth, Grand 



Junction, Colo., 1915. 



Date of 



Num- 



Date of 



Num- 



Date of 



Num- 



Date of 



Num- 



Date of 



Num- 



pupa- 



ber of 



pupa- 



ber of 



pupa- 



ber of 



pupa- 



ber of 



pupa- 



ber of 



tion. 



pupae. 



tion. 



pupae. 



tion. 



pupae. 



tion. 



pupae. 



tion. 



pupa?. 



Apr. 14 



2 



Apr. 26 



13 



May 8 



19 



May 20 



1 



June 1 



1 



15 







27 



8 



9 



13 



21 



1 



2 



1 



16 



1 



28 



25 



10 



4 



22 



1 



3 







17 







29 



13 



11 



26 



23. 



5 



4 



1 



18 



2 



30 



11 



12 



30 



24 



4 



5 







19 



2 



May 1 



4 



13 



20 



25 



2 



6 







20 



3 



2 



1 



14 



12 



26 



2 



7 



1 



21 



7 



3 



3 



15 



10 



27 



2 



8 



2 



22 

 23 





 1 



4 

 5 



3 

 1 



16 

 17 



8 

 7 



28 

 29 



4 

 2 







Total. . . 



320 



24 



4 



6 



3 



18 



4 



30 



8 







. 25 



3 



7 



18 



19 







31 



1 







Length of the pupal stage. — In Table IV will be found the length 

 of the pupal stage of 233 pupae of the spring brood. Reference to 

 this table will show that the first pupation occurred April 14 and 

 the last June 7. The pupal period of the individuals that pupated 

 early in the season was naturally longer, owing to the lower average 



