WERNER MARCHAND 157 



lilac tint of the Malpighian tubules has changed to a salmon color. 

 The latter changes are due probably to a clearing process, in which 

 the larva indulges during the quiescent stage preceding each ecdysis. 



After the second molt the fleshy protuberances functioning as pro- 

 legs become reinforced with a slight cuticular ring at their bases. 

 The mouth-parts at this stage are heavily chitinized. The great 

 hooks or mandibles show a marked serration of the biting edge. The 

 head projects more, exposing the dark brown ocelli, which, prior to 

 the second molt are seen only through the cuticle of the thorax situ- 

 ated nearly on the middle of the concealed head capsule. 



The signs characteristic of the final molt which results in pupation 

 are refusal of food, restlessness, attempted migration, and finally 

 burial in the sand at the bottom of the jar. The body decreases 

 slightly in length, but the thickness remains the same. 



On the extremity of the abdomen, tiny tubercles appear which 

 project more from time to time, becoming tapering and spike-like. 

 Near the caudal end of the abdominal segments, roots of hairs ap- 

 pear. These at first resemble brown spots of pigment and gradually 

 lengthen into stiff brown hairs. The cuticle on the body becomes 

 stiffened and shingle-like at the joints of the segments. The latter 

 telescope less, and one can see numerous particles of sand embedded 

 in the joints of the segments. These sand particles have been car- 

 ried in during the telescopic movements of the abdomen. 



After the fully developed larva passes through a period of semi- 

 dormancy buried in the sand, the skin is seen to be ridged with cutic- 

 ular plates. The head region is reinforced by stiffened cuticle, and 

 the mouth orifice is closed by a plug of hard rose-colored cuticle. 

 This pigmented material lines the entire pharyngeal sinus, plugging 

 the mouth and the cephalopharynx. The cuticular plug has a sub- 

 stantial fold which forms a slit for the passage of the molting mouth. 

 Caudally a similar impervious mass closes the opening of the syphon. 

 A cuticular collar strengthens the base, and the connective tissue 

 surrounding the trachea of the tract of the syphon tends to contract. 

 Then the supports of the central trachea are gradually cast loose by 

 a gentle wriggling of the insect's body. About this time there is a 

 general wrinkling of the epidermis, the folds telescoping upon 

 each other, and the surface becomes like parchment. 



