Carpenter et al. : Mosquitoes or Southern U. S. 



31 



podomyia segment 4 of the fore-tarsus is much shorter than segment 5). 



The fifth or terminal tarsal segment of each leg bears a pair of small 

 claws or ungues, one of which may be much larger than the other on the 

 fore-legs of the males of some genera. Arising between the bases of the 

 claws is a small, hairy empodnun, apparently always present but usually 

 inconspicuous. A pair of small pad-like structures, the pulvilli, arise laterally 

 near the base of the ungues in Culex and is a diagnostic feature of this genus. 

 The ungues often exhibit generic and sexual differences, but since they are 

 so small as to be inconvenient to examine, they are not discussed in detail. 



The vestiture of the legs consists of scales, hairs and bristles, but the 

 scales are by far the most important from a taxonomic standpoint. They 

 are usually rather broad, appressed, and imbricate, but may occasionally be 

 longer, more slender, and suberect, as in the subgenus Psorophora. Ornamen- 

 tation due to the arrangement of contrasting dark and pale scales, particu- 

 larly on the tarsal segments, forms the basis for some of the most useful 

 specific characters. This ornamentation is commonly present as basal, medial, 

 or apical bands of pale scales (often both apical and basal white bands pres- 

 ent on the same segment). The presence or absence of pale markings, and 

 the position and extent of these markings when present, are very frequently 

 used as key differences between species. 



Mesothoracic Wing. — The mesothoracic wings are well-developed organs 

 of flight; their scales and type of venation serve as infallible means of 

 distinguishing the Culicinae from other Diptera. They are elongate-oval in 

 shape, each with two indentations near the base on the posterior margin. The 

 small, flap-like structure nearest the thorax and delimited by the first inden- 

 tation is the squama. In most mosquitoes the squama is fringed with hairs, 

 but this fringe is absent in a few genera, including Megarhmus. Wyeotnyia, 

 and Uranotaenia in the southern states. The area delimited by the second 

 indentation, the small, lobate alula, is of little importance. 



The nomenclature of wing venation adopted here (Fig. 11) is essen- 

 tially that used by Barraud (11), Edwards (56), and Ross and Roberts (150), 



costal cell 



subcostal cell 



fringe 



2nd posterior cell 



Fig. II. 



longitudinal 



Wing of mosquito, with venation shown. C, costa ; Sc, subcosta ; 1. first 

 vein; 2, second longitudinal vein (2.1, anterior branch; 2.2, posterior 



blanch); 3, third longitudinal vein; 4, fourth longitudinal vein (4.1, anterior branch; 



4.2, posterior branch): 5, fifth longitudinal vein (5.1, anterior branch; 5.2, posterior 



branch); 6, sixth longitudinal or anal vein; H-v, humeral cross-vein; 2-3, 3-4 and 4-5, 



cioss-veins. Pt. petiole of vein 2. 



