242 Annals Entomological Society of America [Vol. VIII, 
The excrementa of animals living in the swamp, the decay 
of leaves, branches, carcasses, etc., produce local changes which 
may prove destructive to larve. These larve nearly always 
manage to wriggle away from the influence of such pollution ° 
and these chemical changes hardly ever become general enough 
during the cycle period of the mosquito so as to exterminate 
all breeding. Even the admixtures of oils and larvacides are 
found to be difficult, for it is practically impossible to give 
thorough treatment in all places. The total pollution for the 
entire season can hardly make the environment unfit for 
mosquito larve. The heavy rains of the next rainy season will 
again readjust the environment; therefore such pollution can 
hardly become accumulative. 
II. The Habitat of the Adult. 
The hottest and windiest part of the day is about at noon- 
time, and is the period of least activity in the animal world. 
It is during dawn and dusk that mosquitos sally forth and show 
pronounced activity. During the daytime they are hidden 
in the bush, under buildings, etc. The factors that regulate 
this time-adaptation are light, heat and wind. Among the 
factors which disturb the tranquility of the mosquito world, 
man and his radical measures assume greatest importance. 
Ditches, oil, hydraulic fills and plenty of patience are the tools 
that slowly but surely get at the root of such serious breeding 
and convert it to unfitness for such purpose. 
DYNAMIC RELATIONS OF THE MOSQUITOS. 
A. REVIEW OF THE SALT-MARSH BREEDING AREA. 
The early part of January, 1913, the writer was sent to 
Gatun. The conditions found were really alarming, inasmuch 
as the species involved was a malaria-transmitter, and the 
unscreened, congested town of New Gatun invited a spread of 
malaria. This influx of mosquitos was unexpected and hence 
unprovided for with funds, but the energetic work of LePrince 
and Corrigan, aided by several sanitary inspectors, soon 
brought this danger within control. The following table is 
introduced to show the number of mosquitos actually caught 
during the three weekly periods ending February 15, 1913, and 
the number of reported cases of malaria for the same period. 
