38 
Transactions of the Academy of Science of St. Louts 
ists for North American species, and the following data in the 
main confirm previously determined facts ; but they are of impor- 
tance in indicating the situation as it was found in St. Louis 
County. Table 5 shows the number of specimens of the various 
species which entered houses and barns, information of consider- 
able epidemiological importance. 
'pic alls 
'^ -v...^ u/'tLutw lidi, never ueen louna Ditmg man, me 
knowledge that its larvae are frequently associated with those of 
AnObhelfJ! minrJrimnriilnt,,^ ^U^ i.t.-j. -r i , - i r 
if adequate control of 
■ .f .^-^.^ -i-Mt*, w/.ucHtuii-w Miuws mar it adequate control ot 
this primary malaria carrier is obtained the breeding places of 
C. apicalis will probably be largely controlled also. Larvae asso- 
ciations are shown in Table 6. 
When considered in relation to the type of breeding place 
preferred by each species (Table 7) it is readily understood why 
Aedes vcxans and Culex pipiens would become extremely abun- 
dant under such weather conditions, as prevailed during 1933, 
the year of the greatest outbreak of St. Louis encephalitis. All 
214°?Q^f ^^^^ epidemic (see e.g. Public Health Bulletin No. 
14, 1935) stress the abundance of mosquitoes, and recent work, 
especially that of Reeves, Hammon and Izumi (1942), indicates 
that mosquitoes may be important as vectors of the disease. 
From the table it will be seen that the most usual places in 
which mosquitoes were found breeding were ponds. Anopheles 
qnadnmaadaHcs were largely confined to such areas. Though 
some breeding places do not fall naturally into the categories 
listed above a number of conclusions are justified from the data 
at hand^ The most striking fact is that, while members of the 
gemis Aedes make up 32.9 per cent of adult collections, they 
comprise only 12.6 per cent of larval collections. The situation 
would be even more marked were it not for the omnipresent A. 
vexans A comparable situation was found in the 1938 Massa- 
ZlTuTT? '"'''■">' ''^''^ ^'^'^ formed 34.6 per cent of 
the adults but only 3.9 per cent of the larvae. The reason is prob- 
I 
