Carpenter et al.: Mosquitoes of Southern U. S. 259 



sternite; each plate apically with a long bluntly pointed ventral arm (Ph-VA), 

 sUghtly curved outward and nearly reaching the crown of the tenth sternite; 

 arising laterally near the base of the ventral arm are several stout pointed teeth 

 (Ph-T). Claspette absent. Basistyle (Bs) about two and one-half times as long 

 as basal width, with outer margin curved, portion beyond subapical lobe more 

 slender, and apex bluntly rounded; vestiture of numerous setae, longer on outer 

 aspects. Subapical lobe (S-L) prominent, undivided, armed with two stout 

 rods, two stout setae, and a narrow leaf -like filament. Dististyle (Ds) about 

 half as long as basistyle, curved, gradually tapered, bluntly pointed at tip; claw 

 (Ds-C) short, blunt. 



LARVA. (Fig. 143). — Head broader than long. Antenna shorter than head, 

 rather slender, constricted beyond the antennal tuft, with portion before con- 

 striction spinose, portion beyond constriction darker and with fewer spines; 

 antennal tuft large, multiple, barbed, inserted at outer third, reaching beyond 

 tip of antenna. Head hairs: Preantennal (A) multiple, barbed, reaching to 

 antennal tuft; lower (B) and upper (C) multiple, barbed, extending beyond 

 preclypeus; postclypeal (d) small, single; sutural (e) and trans-sutural (f) 

 usually multiple; supraorbital usually 2 to 4-branched beyond base. Thorax 

 glabrous. Upper lateral abdominal hairs usually triple on segments I to VI. 

 Comb of eighth segment of numerous scales in a patch; individual scale 

 rounded apically and fringed with subequal spinules. Siphon about four and 

 one-half to five times as long as basal width; pecten of about 10 to 15 rather 

 evenly spaced teeth on basal third of siphon; individual pecten tooth with 1 to 

 5 coarse teeth on one side; five pairs of multiple subventral tufts present, 

 all in line, the proximal pair inserted near or slightly before end of pecten. 

 Anal segment longer than wide, completely ringed by the dorsal plate; lateral 

 hair double or triple; dorsal brush bilaterally consisting of a long lower caudal 

 hair and an upper caudal tuft of three hairs, one nearly as long as the lower 

 caudal; ventral brush well-developed, confined to the barred area; gills 4, usual- 

 ly about as long as the segment, each tapering to a blunt point. 



DISTRIBUTION. — Canada; central, southern and western United States; and 

 Mexico. Southern States: Alabama (125); Arkansas (30); Florida and Geor- 

 gia (125); Kentucky (140); Louisiana (96); Mississippi (125); Missouri 

 (1); South Carolina (125); Tennessee (97); Virginia (54). Other States: 

 Arizona, California, Colorado, Idaho and Illinois (52); Indiana (76); Iowa 

 and Kansas (52); Michigan (88); Minnesota (131); Montana (112); 

 Nebraska (178); Nevada and New Mexico (52); North Dakota (127); 

 Oklahoma (159); Oregon (52); South Dakota (129); Texas (108); Utah 

 (142); Washington (52); Wisconsin (48); Wyoming (129). 



BIONOMICS. — The females are fierce biters, attacking at dusk and after 

 dark, and they readily enter houses. The bite is very painful and according to 

 Hearle (78) the swelling and pain last for hours. Larvae occur in either fresh 

 or rather foul water in various types of breeding places, including ground pools, 

 rain water barrels, roadside ditches, and irrigation water. 



MEDICAL importance. — This mosquito has been found naturally infected 

 with the viruses of St. Louis and western equine encephalitis, and it has been 

 demonstrated that it is capable of transmitting the infections. 



