Carpenter et al. : Mosquitoes of Southern U. S. 27 



The moulhparts which He within the labium of the female, listed in 

 order with the most dorsal first, are as follows: (1) The upper lip or labrum- 

 epipharynx, an elongated organ pointed at its apex and inverted U-shape in 

 cross-section; (2) the flat, blade-like hypopharynx, lying directly beneath the 

 labrum-epipharynx and in close apposition to its ventral surface, forming a 

 canal through which liquid food is drawn during ingestion (the hypopharynx 

 itself is traversed by a minute salivary duct leading from the salivary glands) ; 

 (3) the paired mandibles and distally dentate maxillae. The mandibles and 

 maxillae are delicate linear-lanceolate organs, the former lying lateral to the 

 labrum-epipharynx and the latter lying beneath and lateral to the hypopharynx. 



The mouthparts of the male mosquito differ somewhat from those of the 

 female in that the hypopharynx is apparently fused with the labium. The 

 maxillae are delicate structures, greatly reduced in some species. The mandi- 

 bles, when present, are also greatly reduced. 



Torus 



I ^^^^Tx- ^-.====°*^'''^'°''^ ^--labrum-epipharynx 



V^^l«\^ /! ^ -^. ~^ ' mandibles 



1"^--^^;;;;^;^==^;-— _^_~ ■ — ZZir:;;;---- -^_ ^ maxillae 



clypeus I ~^^^~~~----^^^^^IZlZ~~— -— ^^^^11^^ hypopharynx 



palpus labium ~ labellum 



Fig. 9. Mouthparts of female mosquito. 



THORAX (Fig. 10) . — The thorax consists of three fused segments, the 

 prothorax bearing the fore legs, the mesothorax bearing the second pair of 

 legs and the wings, and the metathorax bearing the third or hind pair of legs 

 and the halters or vestigial hind wings. The mesothorax is much more devel- 

 oped than the other segments due to the fact that it contains large, powerful 

 wing muscles. 



Prothorax (Fig. lOA, B). — The prothorax is reduced and consists of the 

 anterior pronotum, a lateral prominence just back of the head; the posterior 

 protiotum, the region behind the anterior pronotum and in front of the 

 spiraciilar area (small triangular area immediately before the anterior spiracle 

 and set off from posterior pronotum by a definite ridge) ; the pro pleura, a 

 small portion just above the fore coxa; and the prosternum, the region be- 

 tween the two fore coxae. The setae and scales of these regions serve as 

 important taxonomic characters in some genera and species. In Uranotaenia, 

 for instance, the propleural setae are reduced in number. Setae known as 

 spiracular bristles arise from the spiracular area in Cidiseta, but are absent 

 in Culex. The posterior pronotum may bear setae or be covered with scales 

 of various types. The anterior pronotum may be clothed with setae and 

 scales, that of the genus Wyeomyia, for example, being shingled with broad, 



