LIFE-HISTORY OF RHIPIPHORUS 



699 



vermiform movement; and at the same time it casts a skin, together 

 with the black head, legs, plates, etc." 



The larva, now in its second stage, passes forward and seizes hold 

 of the upper or lateral aspect of the prothoracic segment of the wasp 

 grub. On emerging it becomes shorter and thicker, " and very soon 

 loses length by that curving forward of its head which is so marked 

 in the full-grown larva, and which does not exist before its emer- 

 gence." The larva is now found "lying like a collar immediately 

 under the head of the wasp grub, and is attached to it by the head, 

 though not very firmly. At this stage the feeding of the young 

 Rhipiphorus is rather sucking than eating. 



When about 6 mm. in length it moults a second time, and the full- 

 grown larva closely though superficially resembles a Crabro or Pem- 



FIG. 646. First larva (a} of Bruchus faba, greatly enlarged; ft, thoracic processes; c, head, 

 from front ; cl, from side ; e, antenna ; f, thoracic leg ; g, rear view of tarsus ; ft, same, front view. 

 After Riley. 



phredon larva, the small head being bent over forwards. By the 

 time it is ready to pupate it has wholly eaten the wasp larva, and 

 the temperature of the cell being high, a larva 5 mm. long grows 

 large enough in two days to fill the top of the cell of its host, and 

 the larva is ready to pupate about a week after hatching, so that its 

 development is very rapid. The beetles themselves do not live in 

 the cells. Chapman thinks they hibernate, and that the eggs are 

 laid in the spring or summer. 



We thus have in this insect three larval stages, the triungulin, and 



