236 Annals Entomological Society of America [Vol. VIII, 
Due to the absence of hills, rains could wash no silt into the 
breeding area, and what was present, settled to the bottom. 
Imperfect drainage prevented currents, though in time stagna- 
tion would follow and make unfit the environment. The latter 
part of January, 1913, a ditch was cut through the swamp, and 
shortly after a pipe-line dredge began to pump silt into the 
swamp. This violent disorder in the environment—current, 
silt and drainage—soon began to tell upon the numbers of 
mosquitos breeding in the swamp. 
Tl. -Burotic Factors. 
The microbiology of the waters of the marsh was not 
studied. Spzrogyra and Oscillaria were found within the 
digestive tract of larvae of A. tarsimaculata and Aedes taento- 
rhynchus, but these green alge can hardly be the only source 
of food since larvee of both species have been found in situations 
devoid entirely of algal growth. The decaying leaves and 
fallen twigs, excreta of animals and decaying animal matter 
favor the growth of micro-organisms, and these probably are 
eaten by the mosquito larve. 
Trees and shrubbery are important factors because they 
furnish the needed protection from intense light and heat, and 
lower the rate of evaporation. So important is this protection 
to the adult that one never sees these small flies active in the 
open during the daytime. However, hunger often changes 
existant physiological states, and so the presence of a man in 
an exposed place near which mosquitos are hidden, may often 
bring these toward him in great number; and the first act to be 
noted is an attempt to sink their proboscis into flesh. But if 
no human being is present, the mosquitos remain in seclusion. 
When so venturing forth to secure a blood meal, they show no 
negative reaction toward heat or light, and may even suffer 
body mutilations without evident consciousness of pain. 
No effort was made to survey the marsh for the animal life 
it contained, but birds were noted to be the most numerous 
next to insects, followed by snakes, lizards, iguanas, monkeys 
and armadillos, the last two rather uncommon. Cows occa- 
sionally strayed into the area and when examined on one occa- 
sion, were found to have their ears well lined with busy 
Anopheles and Aedes. 
