1915] Behavior of Anopheles 269 
ment is considered. Such information may indicate the 
particular places which require strict anti-malarial measures, 
and may eliminate from thorough treatment certain suspected 
areas, thus reducing greatly the cost of sanitation. 
SUMMARY. 
(1). The study of the behavior of mosquitos has important 
value to the sanitary inspector in that this study gives him 
important clues as to the measures to adopt, which areas to 
control, and where best to locate temporary or permanent 
camps. 
(2). The factors of wind, temperature and humidity are the 
most important in the adult mosquito environment. The 
winds at Gatun are relatively high, but they die down con- 
siderably as dusk appears. 
(3). The salinity of the water equalled that of the ocean, 
but did not inhibit breeding. Ordinarily, the water of the 
salt-marsh is greatly evaporated as the dry season advances, 
and its salt content so increased that mosquito larve cannot 
live therein. However, there was an increase of rains the latter 
part of 1912 which so diluted the water of that marsh that the 
subsequent evaporation did not increase the salt content 
beyond the critical point. 
(4). The life cycle of Anopheles tarsimaculata was found 
to be from seven to nine days. 
(5). Direct observations from boats and on land showed 
a distinct flight of hordes of tarsimaculata and teniorhynchus 
toward Gatun, beginning at dusk, and lasting about thirty to 
forty-five minutes. There was a return flight from Gatun 
to the breeding place beginning at early dawn and lasting 
until objects could be easily discerned, about thirty minutes 
duration. This return flight takes place higher in the air, and 
is characterized by haste. 
(6). The flight to Gatun was experimentally proved by 
liberating marked mosquitos at the swamp and later recovering 
them at Gatun. 
(7). Copulation probably takes place on the return flight. 
More males were found near the marsh during the return flight 
than during the evening flight. 
