68 
A Monograph of Culicidae. 
hand. I have observed them for many years hibernating in my 
own house, going into winter quarters in cellars, sometimes in 
October, at others in November, and appearing again in March or 
April. Now and then in warm winters I have found them, like 
Anopheles, flying about in December and January. The hiber¬ 
nating Culex are all pregnant females, the eggs developing 
during the spring. During the past year I kept some under 
observation; their bodies were thin when I took them from the 
cellar, but in about four weeks (April 22nd) they began to swell, 
and later they deposited fertile eggs. They had no meal of 
blood and yet they laid fertile eggs, all of which hatched out. 
In cold regions they sometimes appear before the snow melts 
off the land. A 7 on Hofmann* saw them appear in the Western 
Urals in June before the ground had begun to thaw. The 
Culex common on the Tundra, said to be C. pipiens (probably 
C. nigripes, Zetterstedt), hibernate under the moss. It may 
be taken as a definite law, I think, that Culex and Anopheles 
(except bifurcatus ) normally hibernate during the winter months 
in temperate and Arctic regions, and that even in tropical 
and sub-tropical climates they pass a certain time in a semi- 
dormant state whilst favourable conditions for their increase 
are absent. Mr. Christophers, in his Report to the Malarial 
Commission, tells us f that “ in the dry season in Sierra Leone 
the Anopheles exist in most parts of the town (Freetown) in 
dwellings, especially in overcrowded native huts and native 
quarters, ready to lay their eggs when pools appear.” Amongst 
places in tropical climates where they have been observed in this 
semi-dormant state during the cold or dry weather must be men¬ 
tioned curtain hangings and draperies generally (Giles). More¬ 
over, the same observer states that such places form a favourite 
resting ground for mosquitoes during the hot parts of the day at 
the season when they are most annoying. 
“The fact that mosquitoes hibernate would explain,” says 
Mr. Nuttall, “the occasional occurrence of malaria in winter,” | 
especially when we know that they may come forth from their 
winter quarters at all times. Mochlonyx also probably hibernates, 
but of this and all other genera save Corethra we know little or 
nothing. Corethra passes the winter evidently entirely in the 
larval stage, the larvae either being half grown or nearly 
* “ Reisen,” p. 153. 
f Proc. Roy. Soc., .Tilly 6, 1900. 
X Johns Hopkins’ Hospital Reports, vol. viii. p. 112. 
