60 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
divided in the middle, the lateral segmental spots triangular; venter 
with a black median band or largely black. Legs black, the femora 
more or less whitish beneath and with a few pale scales on the outside ; 
tibiae with a few pale scales. Wing scales black. The male differs 
notably, having no scales on mesonotum or abdomen, but only long 
dense black hairs. It is entirely black, without any light markings. 
The palpi have the last joints thickened and hairy, but only slightly 
exceeding the proboscis. 
The species breeds in early spring pools filled by melting snow 
banks. At the higher levels these commonly melt slowly enough so 
that the larvae can mature; but below 7,000 feet altitude this is not 
always the case. Some pools near the edge of Lake Tahoe which 
were full of larvae of this species dried rapidly and all perished. 
Distribution.—Mountains of Placer County, California. 
United States Records. 
CALIFORNIA: Lake Tahoe, June 20, 1915 (A. K. Fisher). 
Summit, June 22, 1920 (H. G. Dyar). 
AEDES (HETERONYCHA) SPENCERII Theobald. 
Culex spencerii THEOBALD, Mon. Culic., vol. 2, p. 99, 1901. 
A rather small dark-gray mosquito, inhabiting the open grassy 
prairie. Mesonotum dark brown in the middle, a grayish stripe on 
each side on the margin and over antescutellar space. Abdomen 
with diffuse grayish white bands at bases and apices of segments, 
and a line of the same color down the middle, cutting the black 
ground into paired squarish spots; venter whitish. Legs black and 
grayish white, the latter color predominating beneath; femora white 
below. Wings with the costa, first, third, and fifth veins black 
scaled, the alternating ones white scaled. 
The winter is passed in the egg stage, the larvae developing in 
early spring pools. The adults inhabit the open prairie, avoiding 
timber. The males swarm after sunset over prominent objects on 
the prairie. 
Distribution.—Prairies of central Canada and northern edge of 
the United States. 
United States Records. 
NokTtH DaKkoTA: Devils Lake, July 20, 1921 (H. G. Dyar). 
Norwich, July 16, 1921 (H. G. Dyar). 
Tunbridge, July 16, 1921 (H. G. Dyar). 
Rugby, July 16, 1921 (H. G. Dyar). 
Knox, July 16, 1921 (H. G. Dyar). 
Fargo, July 27, 1921 (H. G. Dyar). 
MINNESOTA: East Grand Forks, July 24, 1921 (H. G. Dyar). 
