34 



ENTOMOLOGY 



sucking tube ; the mandibles and maxillae are delicate, linear, piercing 

 organs, the latter being barbed distally; maxillary palpi are present; the 

 hypopharynx is linear also and serves to conduct saliva; the labium forms 

 a sheath, enclosing the other mouth parts when they are not in use; a 

 pair of sensory lobes, termed lobelia, occur at the extremity of the labium. 

 The oesophagus is dilated to form a bulb, or sucking organ, from which 

 muscles pass outward to the skull; when these contract, the bulb dilates 

 and can suck in fluids, as blood or water, which are forced back into the 



mx 



I li h m 

 m m mx 



FIG. 53. Mouth parts of female mosquito, Culex pipiens. A , dorsal aspect; B, transverse 

 section; C, extremity of maxilla; D, extremity of labrum-epipharynx; a, antenna; e, com- 

 pound eye; h, hypopharynx; /, labrum-epipharynx; li, labium; m, mandible; mx, maxilla; 

 p, maxillary palpus. B, after DIMMOCK. 



stomach by the elasticity of the bulb itself, according to Dimmock; the 

 regurgitation of the food is prevented by a valve. 



The male mosquito rarely if ever sucks blood, and its mouth parts 

 differ from those of the female in that the mandibles are aborted and the 

 maxillae slightly developed, but with long palpi, while the hypopharynx 

 coalesces with the labium and there is no cesophageal bulb. 



Hymenoptera. In the honey bee, which will serve as a type, the 

 labrum (Fig. 54) is simple; the mandibles are well developed instruments 

 for cutting and other purposes and the remaining mouth parts form a 



