MOUTH-PARTS 



243 



the solvent action of the saUva. The sucking is done by the 

 pharyngeal muscles. The mouth-parts of the gnats, some of which 

 also feed on plant juices, and others on blood, are more complicated 

 (Fig. 177, A and C). The labium again supports the other parts, 

 and the puncture is made, as before, by the mandibles and maxillae 



Fig. 178. — Head and proboscis of a moth. — -From Borradaile and Potts, The 

 Invertebrata, 2nd edition, 1935. Cambridge University Press. A and B after 

 Metcalf and Flint, C after Eltringham. 



A, Front view ; B, side view ; C, transverse section of proboscis. 



dp., clypeus ; dm., diagonal muscles ; e., eye ; ep., epipharynx ; gal., galea ; Ibr., labruin ; /./«., locking 

 hooks ; Ip., labial palp ; md., mandible ; mxp., maxillary palp ; »., nerve ; tra., trachea. 



acting as stylets, but the food canal is made by the almost com- 

 pletely rolled-up labrum-epipharynx, and the salivary duct 

 runs down an elongated hypopharynx. The end of the labium is 

 expanded into a pair of soft lobes, the labella ; the labium and 

 the structures which it contains are collectively known as the 

 proboscis. Outside this is a pair of maxillary palps. Sucking is 

 carried out by the muscles of the pharynx. Mandibles are absent 

 from the male, and the maxillae are represented only by the palps ; 

 he is further distinguished by having longer bristles on the 



