22 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
The male genitalia have the mesosomal plate large and furnished 
with denticles between the arms, the outer arm serrate. The lobe of 
the sidepiece has three rods, a seta, a leaf, and a seta. The tenth 
sternites have all the spines long and alike. 
The larvae are commonly found in grassy ponds or marshes, often 
in escaping irrigation water. They do not take to artificial re- 
ceptacles. . 
This mosquito will enter houses and may become a considerable 
nuisance in the western part of the country. 
Distribution.—Mississippi Valley and western prairies to the Pa- 
cific Ocean, Mexico to British Columbia. 
United States Records. 
WASHINGTON: Bellingham, May 31, 1917 (H. G. Dyar). 
Oroville, July 28, 1920 (H. G. Dyar). 
OrEcon: Portland (R. P. Currie). 
Hood River, July 9, 1917 (F. R. Cole). 
CaLirorNIA: San Diego, April 14, 1906 (J. M. French). | 
Stanford University, 1901 (I. MacCracken). 
Kelly Hot Springs, June 15, 1916 (W. B. Herms). 
IpaHo: Boise, August 14, 1901 (C. B. Simpson). 
NeEvApA: Reno, November 5, 1915 (H. G. Dyar). 
ARIZONA: Carr, August, 1905 (H. Skinner). 
New Mexico: Springer, August, 1909 (C. N. Ainslie). 
Cotorabo: Boulder, October 15 (T. D. A. Cockerell). 
Kansas: Lawrence, June (. S. Tucker). 
IowA: Ames, October 18, 1905 (H. J. Quayle). 
ILLINoIs: Urbana, September 10, 1904 (A. Busck). 
MIssousI: St. Louis, September, 1904 (A. Buseck). 
TEXAS: Dallas, May 11, 1905 (W. D. Pierce). 
Devils River, May 6, 1907 (F. C. Pratt). 
CULEX (CULEX) THRIAMBUS Dyar. 
Culex (Culex) thriambus Dyar, Ins. Ins. Mens., vol. 9, p. 338, 1921. 
A medium-sized brown mosquito, the mesonotum bronzy brown. 
Abdomen blackish, with basal segmental white bands, widened in 
the middle; venter pale, with angular black marks on the posterior 
borders of the segments, the cusps directed forward. Proboscis 
broadly whitish below, ringed with white in the male and sometimes 
also in the female. Legs black, the femora and tibiae pale below, 
tarsi ringed with white on both ends of the joints, rather broadly so 
on the hind legs. Wing scales narrow and dark. 
The genitalia do not differ markedly from those of tarsalis and 
stigmatosoma. ‘The species is close to stigmatosoma and may be an 
eastern race of it. The larvae have the hairs on the air tube single, 
whereas they are multiple in stigmatosoma. 
