34 
avoids other suitable places in the vicinity — as we think— it is unnec¬ 
essary to make the very careful search for local breeding places in 
the neighborhood of the pond and residence in which A. quadri- 
maculatus is found which is otherwise required, especially if they are 
found in numbers, as at Cheatham’s. One can well imagine that the 
flight to obtain the first meal of blood required for oviposition may 
be farther than subsequent ones, which are the only flights which can 
convey malaria—the impulse to continue the species being greater in 
most insects than the desire for any special kind of food. 
The great flight observed i>y Le Prince at Gatun was associated 
with no increase of malaria. The mosquitoes, A. tars!metadata* came 
a great distance from their breeding place to the nearest sufficient 
blood supply—the village of Gatun —and fed. They apparently 
returned to their breeding places—the closest to the blood supply 
available —to deposit their eggs and did not return. Unquestionably 
they were not in any considerable numbers in these villages after they 
became infective to men— about 11 days after feeding for this form 
in Panama —else there would have been an increase in the malarial 
rate, which did not vary from three-fourths per cent during this 
flight and for many weeks afterwards. The flight at Miraflores 
showed the same picture. 
The data wejhave lead us to believe that the maximum flight of this 
species (^4. quadrimaculatus) is farther than has been usually sup¬ 
posed ; at least, if the production is very great and no sufficient blood 
supply is close. In the matter of flight the different species of An¬ 
opheles should be considered separately. As they differ in so many 
characteristics, it would be an unwarrantable assumption that there 
was for the different species no difference in this. This question— 
the distance of ultimate flight — not only directly concerns our present 
problem — the effect of impounded waters on the incidence of ma¬ 
laria — but is very important in all antimosquito measures against 
malaria. 
RECOMMENDATIONS. 
Recommendations in detail were made in writing and verbally to 
the managers of both ponds for their better sanitation as regards 
malaria. Some of these were being put in force for the pond at 
Parr before we left. 
