SUBORDER JUGATAE 77 



some idea of the proportion of the parts. The whole pupa is 

 4 mm. long and 1.3 mm. wide at its widest point. The head 

 is 0.9 mm. wide and each mandible is 0.7 mm. long. 



The only part of the pupa which is strongly chitinized 

 besides the mandibles is the supporting mouth frame, an 

 oval loop of chitin with which they articulate, the remainder 

 of the pupal skin being exceedingly delicate so that the 

 adult structures can be seen within. The arm-like mandi- 

 bles (fig. 28 B) are firmly joined to the mouth frame. Their 

 inner edge is sharply serrated nearly to the end and the apex 

 is broadened out into a formidable club, the edges of which 

 are armed with several strong teeth. They are moved by 

 strong muscles identical with the abductor and adductor 

 mandibulae found in insects with biting mouth parts. The 

 abductor muscle enables it to make a strong outward swing- 

 ing movement and this is used to tear the tough cocoon 

 and afterwards to dig up through the soil. The small imag- 

 inal mandibles may be found in the bases of the pupal ones 

 by dissection, 



Adults. The specimens observed by T. A. Chapman 

 emerged on March 10, 11 and 12 between six and seven in 

 the morning. The jaws, he says, moved actively and 

 opened so far that they passed one another, the one that 

 had been above sometimes coming to lie below the other. 

 Chapman compares it to the motions of a cabman warming 

 his hands. Having torn open the cocoon and wriggled out 

 of it, the pupa then laboriously digs upward through the 

 earth. The head moves very much, the face is lifted up, 

 and the body is pushed on by the movements of the abdo- 

 men helped by its backwardly projecting hairs. At the sur- 

 face of the ground it lies immovable for some time during 

 which the last acts of transformation take place. Presently 

 the mandibles become immovable even under stimulation, 

 through the withdrawal of the imaginal skin and mandibles 

 together with the strong muscles which remain in the imag- 



