222 Annals Entomological Society of America [Vol. VIII, 
able to direct our crusades of extermination against these 
common enemies of mankind. To stop the spread of insect- 
born diseases is to save lives, dollars and to increase comfort. 
Environment and organism are so closely knitted together 
that a change in the former causes a change in the physiological 
state of the organism. And if the animal cannot endure this 
change in its abode, it must seek a new, more suitable home, or 
perish. Thus our knowledge of the behavior of mosquitos gives 
us clues toward the production of just such changes in the > 
environment of the mosquitos which they cannot withstand. 
Hence human hand may, by means of relatively simple meas- 
ures, reduce the population of disease-spreading species far 
below the critical point of danger, if not actually wipe them out. 
But to actually wipe out of existence in a given region all 
such malefactors would probably be prohibitive on account of 
its cost. Constant vigilance and effort are required to main- 
tain a humid, tropical area free from malaria or yellow-fever. 
The conversion of Colon and Panama cities from filth and 
disease-propagating centers into unusually healthy places, 
stands out boldly as a proof of what can be done. It means new 
birth to business opportunities and makes life worth something. 
The knowledge of the behavior of insects has, therefore, undis- 
puted practical value. 
METHODS OF STUDY. 
1. Field Study. This is by far the most productive means of getting at the correct 
interpretation of the dynamic relations of the mosquitos in their normal 
environment. 
A. By Direct Observation: 
i. From a boat, at all times of the day and night. 
ii. Observations on land, at the breeding place and townsite, with 
and without lights, in tents, with domestic animals, etc. 
iii. Collection and examination of adult mosquitos. 
B. By Experimental Data: 
i. Adult mosquitos were attracted into large mosquito-bar nets, 
at the breeding place, by West Indian negroes. The mos- 
quitos thus caught were sprayed with an aqueous anilin dye 
(Zetek 1913-a) and liberated at dusk at the same place where 
sprayed. The mosquitos caught at the townsite and else- 
where were tested for the presence of color. 
ii. By means of intercepting planes, the sides of which were coated 
with transparent tanglefoot. 
2. Laboratory Study. Due to the separaticn of the mosquito from its normal 
environment, but few laboratory experiments were attempted. These were 
simple and only to learn the responses to single factors, such as light 
intensity. 
