58 



LEAF-MINING INSECTS 



and the hypopharynx. These together form a sort of 

 sheath in which the saw edges of the mandibles move back 

 and forth. They cut through the cells and set free their 

 juices which are then sucked in through the sheath or funnel 

 and are swallowed. 



Even in such tissue-feeding forms as Aphelosetia and 

 Nepticula there is reduction or modification of the spinneret 

 and labial palpi, an increase of the hypopharynx to form a 



Fig. 24. A series of labra of sap-feeding leaf -miners. (After Traegardh.) 

 A, Parornix, B, Gracilaria; C, Lithocolletis; D. Phyllocnistis. 



flat lamina and a great increase of the stipes of the maxillae ; 

 but in the sap-feeders these specializations are carried to the 

 extreme, so that while several organs, as the mandibles, 

 labrum, hypopharynx and labium, have attained a very 

 considerable size, others, as the maxillary and labial palpi 

 and the spinneret, are almost or entirely atrophied. The 

 condition is one of the most unique in the insect world. 

 Pupa. As in the larva, so in the pupa, we find a curiously 



