301 



indicate, perhaps, affinities with the Chrysomelidae, and are evidently 

 of advantage in aiding the young creature in the work it has to (h). 

 This stage is very evanescent, as the necessity for locomotive organs is 

 transitory. Immediately after finding the proper spot for entering the 

 bean, the larva gnaws its way in and molts. 



J-y-r^^ 



Flo. 43. — a, First larva of £ruchus/abcegresMy enlarged; b, thoracic processes; c, head from front; 

 d, .same from side ; e, antenna ; /, thoracic leg ; g, rear view of tarsus ; h, same, front view, still more 

 enlarged (original). 



Other eggs hatched on February 10, and February 17, and on Febru- 

 ary 21 a small discolored spot was discovered on one of the beans, and 

 underneath the skin was found one of the young larv«. After enter- 

 ing the bean it had cast a skin, which was found in the burrow. After 

 this molt the larva had lost its legs and become stout, acquiring the 

 normal characters of its later stages. One bean which was carefully 

 examined contained 17 larv.ne, 8 of which were nearly full-grown, while 

 9, which had entered the bean later, were in different stages of devel- 

 opment. On January 28 a single impregnated female was confined 

 with several beans in order to ascertain the number of eggs laid by 

 a single individual. From January 31 to February 25, 68 were de- 

 posited, when the female died. Careful experiments with isolated indi- 

 viduals were conducted in order to ascertain the exact length of a single 

 generation, with the result that sixty-six days was found to be the av- 

 erage time from the deposition of the eggs to the issuing of the adults. 



The larva before transforming frequently makes two possible points 

 of future exit, one at each end of its burrow, and occasionally the whole 

 outer surface of the burrow remains covered simply by the thin outside 

 skin of the bean. 



The remark which we have just made regarding the germination of 

 weeviled peas, will apply equally well to beans damaged by Bruchus. 



