12 



BULLETIN 902, U. S. DEPARTMENT' OP AGRICULTURE. 



Owing to the extreme delicacy of the larva?, it was impossible to 

 rear large numbers at any one time. The small numbers of beetles 

 which developed showed little disposition to breed and it was not 

 possible to determine the number of generations occurring annu- 

 ally from any given "stock," or lot of specimens. The rearing 

 records obtained, however, indicate the probability of three genera- 

 tions occurring annually in Otero County, Colo. 



In Tables II, III, and IV records of the observed generations of the 

 western cabbage flea-beetle in 1916 are given: 



Table II. — First generation of western cabbage flea-beetle . 



Item. 



First, 

 genera- 

 tion. 



Adults captured and confined 



First eggs deposited 



First eggs hatched 



First larva? pupated 



First adults developed 



Egg stage 



Larval stage 



Pupal stage 



Total duration 



1916. 



Apr. 10 



14 



24 



May 23 



June ' 3 



Days. 



50 



Table III. — Second generation of the western cabbage flea-beetle. 



Item. 



Beetles confined 



First eggs deposited . . 



First eggs hatched 



First larva? pupated . . . 

 First adults developed 



Egg stage 



Larval stage 



Pupal stage 



Total duration. . 



Second 

 genera- 

 tion. 



. 1916. 



June 24 

 26 



July 1 

 19 

 25 



Days. 



29 



Table IV. — Third generation of the western cabbage flea-beetle. 



Item. 



Beetles confined 



First eggs deposited. . 



First eggs hatched 



First larva? pupated . . . 

 First adults developed 



Egg stage 



Larval stage 



Pupal stage 



Total duration . . 



Third 

 genera- 

 tion. 



1916. 



Aug. 8 

 12 

 19 



Sept. 10 

 20 



Days. 



