I. TRÄGÅRDH, LEPIDOPTEROUS LEAF-MINERS. 



45 



In these two genera the larva?, at a certain time, quit the 

 mines after having previously undergone an ecdysis which 

 transformes them into larvse of the common type, and subse- 

 quently are external, although concealed, feeders. 



The larva of Lithocolletis, on the other hand, leads to a 

 certain extent the life of a miner, even after having under- 

 gone the ecdysis transforming it from the sap-feeding type, 

 since it does not leave the mine, but remains there until it 

 is full-grown, when it spins a cocoon and pupates. 



Fig. 65. 



Fig. 66. 

 Fig. 67. 



Phyllocnistis sufjusella Zell., last instar. 

 Head, ventral aspect. X 71. a. antenna, sm. submentum, Ib. 

 labrum, 



Head, dorsal aspect. X 71. Ib. labrum. 

 Spinning-apparatus (sp.) and maxillae (mx); t. silk-thread. X 386. 



It is almost of the normal type, the head pointing ob- 

 liqnely downwards, and it feeds on the parenchyma consti- 

 tuting the floor of the mine. It differs, however, from the 

 external feeders by the more pointed head and the great 

 development of the hypopharynx which recalls that of some 

 amongst the tissue-feeders. 



Phyllocnistis differs, as above-mentioned, from all miners 

 yet known, in that respect that all instars, except the last, 

 are of the sap feeding type, while the last instar does not 

 feed at all, and, as a matter of fact, is incapable of doing 



