ANATOMY AND PHYSIOLOGY 



43 



ent; the hypopharynx is linear also and serves to conduct sa- 

 liva; 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. 



FIG. 53- 



mx 



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, 

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

 maxilla; p, maxillary palpus. B, after DIMMOCK. 



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

 from which muscles pass outward to the skull ; when these con- 

 tract, the bulb dilates and can suck in fluids, as blood or water, 

 which are forced back into the 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 



