10 BULLETIN 812, U. S. DEPAKTMENT OP AGRICULTURE. 



time required for the complete development of the larval stage va- 

 ries under differing temperature conditions, and depends upon the 

 condition of the seed in which it develops. Under the most favor- 

 able conditions, as observed by the writer, the larvae completed de- 

 velopment in 12 days. In early spring this period was prolonged 

 to 30 days. 



PERIOD OF AESTIVATION. 



The factors of greatest influence in the life cycle of B. funehris 

 are those which determine the period of aestivation. Larvae of this 

 species, reaching their full larval development in soft green seeds, at 

 once transform to the pupal stage and soon emerge as adults. On 

 the other hand, if the infested seeds mature and harden before the 

 larval development is fully completed aestivation follows. This 

 resting period frequently continues throughout the remainder of the 

 season, or until conditions become favorable for pupation and trans- 

 formation to the adult stage. 



Atmospheric humidity, temperature, and irrigation are important 

 factors determining the duration of aestivation. Aestivation occurs 

 frequently in the larva? of B. funebris during the months of July, 

 August, and September. Favorable conditions may at any time 

 cause transformation to the pupal stage or aestivation may continue 

 into hibernation. The transforination usually occurs at any time 

 between March and July of the following season, though in ex- 

 ceptional cases the larval stage may be continued into the second 

 year. 



Alfalfa seeds collected in the fields on September 24, 1912, and 

 kept dry in the laboratory showed adults of B. funehris emerging 

 throughout the season of 1913 and larvae living in the seeds until the 

 spring of 1914. The last adults of B. funehris emerged as late as 

 September, 1914. This habit causes great diffusion in the adults of 

 the species. It was found that some of the progeny of a single adult 

 developed and reached maturity in about 30 days, while other 

 progeny from the same adult and from eggs deposited on the same 

 day did not mature until the next year. 



PUPATION. 



The period of pupation in early spring requires an average of about 

 30 days, as shown by Table II. As the season advances and the days 

 become warmer the duration of the pupal period is much shortened. 

 Pupae developing in midsummer have a pupal period of from 6 to 10 

 days, and under the most favorable conditions this period is without 

 doubt shorter than that observed in the breeding cages. 



