THE MOSQUITOES OF THE SOUTHEASTERN STATES 69 



4. Mesosomal plate with two arms and with a median row or group of 



four to seven short, stout teeth 5 



Mesosomal plate without a median row of teeth, the processes consist- 

 ing of a short lateral arm and a longer posterior arm, which has a 

 small tooth near the base. (Subapical lobe of sidepiece with three 

 rods, a leaf, and two setae) Culex restuans 



5. Dorsal arm of mesosomal plate short, bent in middle at a right angle 



(thumblike), with a pointed tip; subapical lobe of sidepiece with 

 three rods, a leaf, and two setae; spines of tenth sternite all sharp- 

 pointed Culex salinarius 



Mesosomal plate with a stout, straight, dorsal arm from near base; 

 lobe of sidepiece with only one seta after the leaf (apically) ; spines 

 on one side of tuft of tenth sternite short and bluntly rounded 



Culex nigripalpus 



6. Subapical lobe of sidepiece with distinct divisions ; comb-shaped portion 



of tenth sternite bent inward nearly at right angles; mesosomal 

 plate with a long, curved, basal arm, directed ventrally (basal hook) 



Subgenus Melanoconion 7 

 Subapical lobe not distinctly divided ; apex of tenth sternite less strongly 

 curved ; mesosomal plate without basal hook ; outer end of mesosomal 

 plate studded with small tubercles- Subgenus Neoculex. Culex apicalis 



7. Basal division of subapical lobe of sidepiece divided into two subequal 



arms, each with a long, stout, capitate filament at tip; stem of 



clasper comparatively slender 8 



Basal division of subapical lobe with one arm bearing a stout filament 

 at tip and a second filament arising from a tubercle near the base ; 

 apical division of lobe with a very large, fan-shaped leaf; clasper 

 greatly enlarged apically, the stem stout and constricted near middle ; 

 sidepiece subspherical, with a dense patch of fine hairs on inner sur- 

 face Culex peccator 



8. Apical swelling of clasper cap-shaped, tapering abruptly ; lobe of side- 



piece without an expanded leaflet; ninth tergite with a widened 

 plate, the lobes projecting from its posterior corners as a pair of 



short arms Culex pilosus 



Apical swelling of clasper moderate, gradually tapered; lobe of side- 

 piece with an expanded leaflet on the apical division ; lobes of ninth 

 tergite ovate, prominent, with numerous hairs— Culex erraticus 



KEY TO GENERA 



1. Abdomen with a vestiture of fine hairs ; female palpi as long as proboscis ; 



male palpi long, clubbed at tip; scutellum rounded 



Tribe Anophelini, genus Anopheles 

 Abdomen covered with flat scales; female palpi much shorter than 

 proboscis ; male palpi long or short, not clubbed at tip 2 



2. Proboscis rigid, outer half tapered and strongly curved downward ; 



scutellum evenly rounded and scaled 



Tribe Megarhinini, genus Megarhinus 

 Proboscis flexible, not bent downward; scutellum trilobed, with sepa- 

 rated tufts of setae Tribe Culicini 3 



3. Wings with second marginal cell less than half as long as its petiole 



Uranotaenia 

 Wings with second marginal cell at least as long as its petiole 4 



4. Postnotum with a tuft of setae; squamae without a fringe of hairs 



Wyeomyia 

 Postnotum bare ; squamae with a fringe of hairs 5 



5. Postspiracular bristles present; segment 7 of abdomen narrowed, seg- 



ment 8 much narrowed and retractile 6 



Postspiracular bristles absent (except in Mansonia titillans, in which 

 wing scales are very broad) ; segment 7 of abdomen not narrowed; 

 segment 8 short but not retractile 7 



6. Spiracular bristles present; dorsal segmental pale scaling of abdomen 



usually apical ; mesonotum with at least some broad appressed scales 

 or (in subgenus Gradhamia) with simple claws in female 



Psorophora 



Spiracular bristles absent ; dorsal abdominal pale scaling usually basal ; 



scales of thorax narrow or only slightly broadened Aedes 



