1934 ] 
Mosquito Investigations in Alaska 
207 
The mosquitoes found to be developing in the temporary 
situations represented several species, many of which were 
troublesome. The water in these pools resulted from two 
sources, the more important of these being the melting of 
the snow. The subsequent accumulation of water in small 
pools provided excellent breeding places for the development 
of the larvae from the overwintering eggs. The second 
source was not of as much consequence, being the result 
of the thawing of the frozen ground ; the water rising to the 
surface and forming new pools or adding to the pools which 
had resulted from the melting of the snow. During some 
seasons it is possible that the rainfall during April and May 
may result in the formation of pools similar to those formed 
by the melting snow. Such a condition did not exist dur- 
ing 1931 ; water from rainfall acted in a contributory ca- 
pacity, viz., replenished pools so that the water remained 
long enough to allow larvae to complete their normal de- 
velopment. 
Although the number of species present was rather large 
only four, A. punctor, A. communis, A. aldrichi and A. stim- 
ulans were present in large numbers. As far as is known, 
the life histories of these four species are very similar, the 
general description which follows being equally applicable 
to all. The eggs are laid in summer on moist or dry ground 
and remain unhatched until after having been exposed to 
winter cold. Early in the spring when rising temperatures 
cause the accumulated snow and ice to melt forming pools 
on the frozen ground, the eggs hatch and the first stage lar- 
vae appear. During 1931 some larvae reached maturity early 
in June, pupation being first noted on June 8. Adults of A. 
communis, A. punctor, and A. aldrichi appeared about the 
same time in the middle of June and were present in notice- 
able numbers throughout the same period (Table 2) during 
the season. A stimulans appeared somewhat later and was 
present in numbers throughout a longer period than the 
other three. Information pertaining to the distribution and 
relative abundance of these troublesome species was col- 
