YELLOW FEVER EXPEDITION 
54i 
Culex fatigans. Wied 
Distribution. This is the common house mosquito of the city, in this respect 
resembling S.fasciata, but differing in being a night insect ; although found in and 
about the city and on lighters lying in the river. It was not very common about the 
Hospital Domingos Freire (yellow fever), and about the first occasion it was met 
with there was coincident with the occurrence of a spontaneous yellow fever case ; 
S. fascia ta, on the other hand, was abundant there. It was not met with in huts 
away in the forest ; nor did it come on board the steamers while going up the 
river. 
Breeding Places. This species seems especially to affect foul waters ; larvae 
were found abundant in stagnant pools of stable runnings, and also in a cesspool, 
the covering of which was damaged. Larvae were not met with in puddles in the 
forest. All attempts to breed it from the egg in clean water in the laboratory resulted 
in death of the larvae a few days after hatching. In fact, it seemed to be essentially 
a ' filth ' loving insect. 
Habits of Adult. This species seems to be a purely night insect ; often a 
crowd of males would appear just after dusk in our chalet. Numbers of females 
full of blood were easily obtainable in houses in the city. The eggs are laid in a raft 
of vertically disposed black eggs. 
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