254 MAINE AGRICULTURAL EXPERIMENT STATION. 1917. 



LENGTH OF THE SECOND LARVAL INSTAR. 



A record which was kept of 340 larvae which molted to the 

 second instar between July 18 and July 30 inclusive may be tabu- 

 lated as follows : 



65 molted to the third instar in 7 days ; 210, in 8 days ; 65, in 9 days ; 



average 8.0 days. 



LENGTH OF THE THIRD LARVAL INSTAR. 



A record which was kept of 95 larvae which molted to the 

 third instar between July 27 and August 30 inclusive may be 

 tabulated as follows : 



5 entered soil in 9 days; 11, in 10 days; 3, in 11 days; 11, in 12 days; 



4, in 13 days; 38, in 14 days; ll,*in 15 days; 12, in 16 days; average 



13.2 days. 



LENGTH OF PREPUPAL PERIOD. 



A record which was kept of 215 prepupae which entered 

 the soil between August 7 and August 30 inclusive may be tabu- 

 lated as follows : 



9 pupated in 4 days; 19, in 5 days; 82, in 6 days; 56, in 7 days; 11, 



in 8 days; 11, in 9 days; 6, in 10 days; 8, in 11 days; 6, in 12 days; 



3, in 13 days; 2, in 14 days; 0, in 15 days; 1, in 16 days; 0, in 17 



days; 1, in 18 days; average 7.0 days. 



LENGTH OF THE PUPAL STAGE. 



A record which was kept of 34 pupae which transformed 

 between August 11 and September 6 inclusive may be tabulated 

 as follows : 



2 adults emerged in 8 days; 7, in 9 days; 1, in 10 days; 18, in 11 



days ; 5, in 12 days ; average 10.2 days. 



VARIATIONS IN THE REQUIRED TIME. 



It was observed that whether the eggs were deposited early 

 or late in the season had no bearing on the number of days occu- 

 pied by the different instars, nor did the length of any given 

 instar affect the length of the next instar. However, if the third 

 instar were of short duration, the prepupal period tended to be 

 longer than normal, and conversely. The principal factors 

 causing variation were the conditions of temperature and mois- 

 ture. 



