DISTANCE OF FLIGHT 273 
Neumann at Rio de Janeiro. They state that a draft is undoubtedly disagree- 
able to calopus. On this account they searched for it in vain in exposed situa- 
tions accessible to wind, as for example the Monte da Providencia within the city. 
It would seem that the yellow-fever mosquito does not fly very far and the fact 
that it is very rarely found away from houses supports this view. Carter points 
out that it probably never flies high, and that it is found by preference in the 
lower stories of houses. The same writer in 1904 suggested that the problem of 
flight be investigated as of importance in determining the anchorage of vessels 
in yellow-fever ports. He say on this point: 
“So far he knows of no direct observations on this subject, except those of 
Goldberger at Tampico, and of Grubbs at Ship Island Quarantine. The latter 
found Stegomyie aboard three vessels from Vera Cruz, two of which claim to 
have lain a half mile from shore. He believed they came aboard at Vera Cruz. 
The observations of Goldberger will be given later. 
“ Although direct observaticns on this problem are few, yet there are certain 
indirect ones, bearing, however, entirely on the aérial conveyance of the Stego- 
myia infected with yellow fever. It is notorious that yellow fever is usually 
conveyed but a short ways aérially, ‘across the street,’ or, more often ‘to the 
house in the rear,’ which is about as far as it was expected to be thus conveyed. 
This represents a maximum distance of about 75 yards. The two longest dis- 
tances recorded in recent times of aérial conveyance, one of 225 meters (Mélier) 
and one of 76 fathoms—456 feet (the writer) are entirely exceptional. So much 
for the distances which the (infected) Stegomyia is conveyed—or rather usually 
conveyed—aérially. 
“ On the other hand it is known that vessels moored in certain districts of the 
Havana harbor did not develop yellow fever aboard, except in those who had been 
ashore, or unless they lay close to other vessels which were infected. This ex- 
periment hus been made on so large a scale—with so many vessels and for so 
many years—that we must accept as a fact that an infected Stegomyia was not 
conveyed aérially from the Havana shore to those vessels, or, allowing for errors, 
was very rarely so conveyed. This distance which had been found safe was some- 
thing over 200 fathoms—1200 feet. The prevailing wind was generally slightly 
on shore, but was not constantly blowing. Whether there is any difference in 
the distance to which infected or non-infected mosquitos are conveyed, is, of 
course, entirely a matter of surmise. There is no apparent reason why there 
should be. Yet the infected Stegomyie have almost certainly become so in a 
house; and with their very domestic habits must be found out of doors, where 
they would be subject to conveyance by the wind, in much smaller numbers than 
the uninfected insects, and consequently a lesser number of them would be con- 
veyed aérially. Observation is needed on this subject—the distance (across 
water) that Stegomyie are aérially conveyed. nape 
“ Goldberger, very ingeniously, suggests that on account of its diurnal flight, 
the direction of the wind during the day only need be considered in estimating 
this factor in their aérial conveyance, and states that at Tampico he failed to 
find Stegomyie aboard vessels lying, for ten or fifteen days, about half a mile 
from a place on shore where they were abundant, while numbers of Anopheles 
albipes * and Culex pungens + were found. The wind was on shore during the 
day and calm or off shore during the night. The importance of this point is 
obvious, as on the coast, except when overborne by the trades, the direction of the 
wind is very generally different by day and night.” 
* Anopheles albimanus Wied. 
+ Oulex quinquefasciatus Say. 
