6 BULLETIN 1243, IT. S. DEPARTMENT OF AGRICULTURE. 



LIFE HISTORY AND HABITS. 



The adult (PI. IV, .-4) begins to feed immediately on arrival in the 

 bean field from winter quarters. Females may begin to lay eggs 8 

 days after emergence from hibernation and possibly sooner, but the 

 majority feed for a longer period, the average time being 14 days for 

 6 females in 1922. The adult feeds on the under surface, usually 

 puncturing the leaf and leaving ragged holes, some very small, 

 others one-fourth inch across. Only a very small percentage of 

 feeding takes place on the upper surface. 



Mating occurs in most cases in the fall, but also in the spring. 

 The abdomen of the gravid female gradually becomes distended, and 

 is noticeably enlarged 24 hours before oviposition. Females are 

 then easily distinguished from males. An individual female has 

 deposited as many as 1,669 eggs during a season. Eggs are usually 

 laid in groups of from 40 to 60, averaging 51 for females observed by 

 the writers in 1921 and 1922. Eggs (PL IV, B) are almost invariably 

 placed on the under surface of the leaves in rather compact groups. 

 In midseason a female will deposit a group of eggs quite regularly 

 every two or three days until death. 



The egg-laying records of a few representative females chosen from 

 69 complete experiments in 1921 and 1922 are given in Table 1. 

 Included also is the time between emergence and the first egg laying. 

 The beetles of the fourth generation did not lay eggs. The records 

 of mating are the observations made while attending to the experi- 

 ments and are not complete. Each experiment included a male and 

 female, except in the cases noted. 



Table 1.- 



-Egg deposition records of a few representative females of the Mexican 

 bean beetle in cages, Birmingham, Ala., 1921 and 1922. 



1921. 



OVERWINTERED FEMALES. 

 No. LiH-O: Female collected in field March 26; more than 10 days between emergence and first eggs. 



Apr. 5... 



8... 









Eggs. 

 68 



72 



May 12 



15 



17 



20 



23 



25 





Eggs. 



60 



55 



60 



53 



64 



54 



May 2S 



31 



June 3 



7 



Total 





Eggs. 

 58 

 53 



14 

 21 

 26 

 30 

 May 9... 









74 

 48 

 68 

 72 

 63 



52 

 31 



1,005 



No. LH4- 



-2: Female 



dormant from hibernation 



jage March 24; 42 days between removal and first eggs. 



May 5 

 13 

 18 

 22 









Eggs. 

 61 

 56 

 57 

 56 



May 24 



26 



29 



June 1 





Eggs. 



57 



58 



58 



58 



June 6 



9 



Total 





Eggs. 

 54 

 57 



572 











FIRST GENERATION FEMALES. 









No. 



LH-4G: 



Female emerged May 20 



11 



days between emergence and first 



eggs. 





May 31 . . 









Eggs. 

 47 







Eggs. 

 54 



July 6 



8 





Eggs. 

 55 











41 

 53 

 52 

 59 

 55 

 55 

 .. 55 



22 



26 



282 



30 



July 2 



32 



5 





57 



53 



56 



53 



54 



55 



51 



7 



9 

 13 

 15 

 17 

 19.. 



11 



13 



Total 





54 

 54 



1,013 



i This female had no opportunity to mate in 1921. All groups deposited were normally fertile. 

 2 Mating observed this date. Females paired when emerged except in case of LH-9 and LH4-2, 1921, 

 which were isolated. 



