I ANATOMY AND PHYSIOLOGY 41 



Diptera. In the female mosquito the mouth parts (Fig. 55) are 

 ong and slender. As Dimmock found, the labrum and epipharynx 

 combine 1 to form a 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 labella, occur 

 at the extremity of the labium. 



I li h m 

 mx m m mx 



D 



FIG. 55. Mouth parts of female mosquito, Culex pipiens. A, dorsal aspect; B, trans- 

 verse 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 contract, 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 having the mandibles aborted and the 

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

 coalesces with the labium and there is no oesophageal bulb. 



1 Kulagin, however, described them as remaining separate. 



