10 THE YELLOW-FEVER MOSQUITO. 
are favorite breeding places. The larve occur in tree holes only when 
the latter are in close proximity to human habitations. 
BEHAVIOR OF LARVZ. 
The larve (fig. 5), when suspended from the surface film of the water 
to take in air, hang almost perpendicularly. They are very easily 
alarmed and then go quickly to the bottom, where they remain a con- 
siderable time. They can live under water for a long time without 
rising to the surface. When water is poured from a receptacle 
inhabited by these larve they quickly 
seek the bottom, and their presence 
may not be suspected, although the 
vessel is in constant use. They cling 
so closely to the bottom that unless 
the jars are rinsed and tipped up so as 
.to empty them completely, which is 
not usually done, nearly all the larvee 
will remain in the jars. On account 
of this habit they are not easily dis- 
posed of by pouring out the contents 
of a barrel. 
FOOD HABITS OF LARVZ. 
The larve occur most frequently in 
clear water in rain-water barrels or 
in drinking-water receptacles in houses. 
The water in such receptacles con- 
tains more or less animal matter 
as well as vegetable refuse, and such 
probably is generally the food of the 
larve. The larve feed at the bottom, 
oS where they mouth over the organic 
Hic. \bThe yellowfever mos.) seuument,even when the water is very 
quito: Larva. Much enlarged. deep. Larve in confinement may be 
ees observed chewing vigorously on dead 
insects or larval or pupal cast skins. They are sometimes canni- 
balistic, the larger larvae devouring the smaller ones. 
The growth of yellow-fever mosquito larve is hastened by the 
presence of a small amount of fecal matter in the water. Observers 
in Habana at the time of the Cuban war found that the larvee which 
bred in the tin cans used for carrying away human excrement from 
the hospitals developed rapidly, and other observers have recorded 
the fact, that by adding fecal matter to the water in which were 
BAT 
