deer UD BOs Nes BU LErTsliN 2 
of the Des Plaines Valley district, and J. Lyell Clark, engineer for that 
district; and Mr. Howard C. Phillips, representing the North Shore 
district. Dr. C. W. G. Eifrig, president of the Illinois Audubon Society, 
presided. 
The problems of these districts were presented in detail and control 
methods discussed with reference to possible injury to wild life, and to 
birds in particular. Mr. J. Lyell Clark gave a general outline of the 
life cycle of the mosquito and the relative prevalence of different species, 
and described the control methods designed to abate the most troublesome 
species occurring in the Chicago region. It was brought out that there 
are twenty-one species to be reckoned with in the region, these being classi- 
fied into three groups according to their breeding habits: the woodland 
group, the marsh and the domestic groups. 
Mosquitoes of the woodland group have but one brood each season. In 
order to control this group the highly discolored brown water, overlying 
leafy woodland pools and stump holes, requires oiling once each year, about 
the middle of April. 
Mosquitoes of the marsh group are travelers, several species being 
known to fly as far as three miles. A very common species of this group 
breeds in the casual water of prairie marshes and field pools following 
long wet spells in June and July. At such times 90 per cent of all mos- 
quitoes disturbing us are dedes vexans, a member of the marsh group. 
At such times this species becomes very annoying in the garden as it flies 
from its breeding place, the field pool, to seek shelter in yard shrubbery, 
where it may also secure a blood meal. “The Mosquito Abatement district’s 
drainage program, directed toward the eradication of this species of the 
marsh mosquito, is to extend over a period of five years and is now in its 
third year. 
Mosquitoes of the domestic group, under ordinary circumstances, may 
be controlled by careful investigation of home premises and removal of 
water containers about the house and yard, together with the oiling of 
street catch-basins. However, there is one very important exception to this 
rule, i. e., the enormous production which takes place in large bodies of 
polluted water, such as the rivers and streams in the Chicago area. In our 
clean rivers and streams, in fact in these same rivers and streams beyond 
the zones of pollution, fish keep mosquito production down to a minimum, 
whereas in the polluted zones unrestricted mosquito production is so great 
as to cause what may be termed a mosquito scourge in certain districts. 
Mr. Clark said that control measures directed against mosquitoes of 
the domestic group conflicted in no way with the presence and well being 
of desirable birds, fish and flowers, and that in point of fact the fight which 
is being waged by the Mosquito Abatement district for clean streams is in 
harmony with the aims of the Izaak Walton League and other groups 
