INSECTA 



497 



The next important line of evolution is that concerned with the 

 development of a mechanism for obtaining juices from deeply placed 

 nectaries of flowers. For this purpose, e.g. in Apis^ the honey bee 

 (Fig. 343), a complicated tubular proboscis is formed. The glossae 

 of the labium have become fused and elongated, the paraglossae 

 remaining small. The labial palps enclose the fused glossae (median 



^%{{+^C 



Fig. 344. Caterpillar of Lepidoptera, A, B, C, and of Hymenoptera, D, E. 

 A, Larva of Tryphaena pronuba. B, Its head capsule. C, An abdominal leg. 

 D, Larva of apple sawfly, Hoplocampa testndinea. E, Head capsule of latter. 

 an. antenna; dp. clypeus; /r. frons; lb. labium; Ibr. labrum; ind. mandible; 

 mx. maxilla; oc. ocellus; v. vertex. 



lobes of the labium), they being concave on their inner surfaces. 

 Outside these the large hood-like galeae of the maxillae form an 

 additional enclosing jacket. 



The glossa is grooved along its dorsal surface and fluid passes up 

 this by capillarity, assisted by movements of the proboscis. It is 

 finally pumped up by pharyngeal action, the labial palps and maxil- 



