268 MOSQUITOES OF NORTH AMERICA 
Simond, Aubert and Noe, in their work on the epidemic of yellow fever in 
Martinique in 1908, carried away by this idea, insinuate at frequent intervals 
that the transmission of yellow fever takes place only at night. At a certain 
point, where they discuss the abundance of calopus during the hot months, they 
formulate this doctrine as follows: “C’est en se basant sur cette considération 
que la mission estiina dangereux, au mois de janvier, le retour des fonctionnaires 
européens dans la ville, 4 moins qu’ils ne fussent astreints 4 se protéger la nuit 
dune maniére efficace contre les piqiires de Stégomyias.” * This is a complete 
inversion of biological facts. Aédes calopus is a diurnal mosquito and nocturnal 
bites, if they occur in darkness at all, are certainly rare exceptions. The erro- 
neousness of the views of the French investigators is clearly brought out in their 
remarks on the copulation of calopus. ‘“ Deux fois seulement nous avons eu 
Poccasion d’observer l’accouplement: il a lieu presque toujours dans la nuit et 
4 Pobscurité, d’ot la rareté des observations de ce genre.” + The testimony of 
many good observers is that where calopus is abundant copulation can be fre- 
quently observed in the daytime. Goeldi, for example, says: “ teml-a visto mil- 
hares de vezes e a vémos todos os dias” (“ we have seen it thousands of times 
and we see it every day’). 
1910, vol. 13, p. 253). Under “ Regulations to be enforced at foreign ports infected with 
yellow fever ’’ we read the following : 
“The vessel shall not lie where her crew will be exposed to the danger of ccntracting yellow 
fever, and at ports where the vessels lie at wharves the vessel must be moved into the stream 
or at least 200 meters from the wharf before sunset, and not returned to the wharf before 
sunrise the following day..... “s 
It was difficult to believe that an American medical department which had been in close touch 
with the work of our Army surgeons in Cuba, and afterwards conducted investigations on its 
own account which were entirely confirmatory, should accept the French contention that Aédes 
calopus bites only at night. It was therefore decided to make inquiry of the head of the 
Public Health and Marine Hospital Service and in reply we received the following letter: 
Treasury Department, Washington, January 26, 1911. 
Dr. L. O. Howarp, 
Chief of the Bureau of Entomology, 
Department of Agriculture, 
Washington, D. C. 
My dear Dr. Howard: 
I have been unable before this time to answer your letters of January 14 and 16, owing to 
the extreme pressure of official business. 
In regard to the activity at night of the yellow fever mosquito, and the idea as to this 
activity, conveyed by the phraseology of paragraph 9 of the foreign fruit regulations, I have to 
say that it is necessary for quarantine administrative reasons that some measure be devised to 
hold on board between the hours of sunset and sunrise, the crews of vessels which are lying 
in ports infected with yellow fever. In the day time the crew is under control while the vessel 
is alongside the wharf. If the vessel should be allowed to remain at the wharf at night 
the sailor man would be free to visit such dangerous surroundings as lighted music halls, 
saloons, and other resorts, but removed to mid-stream, between the hours of sunset aud sunrise, 
he cannot convenicntly reach such points. It is impossible to control the mosquito problem in 
any foreign port, and therefore the only recourse is to attempt to control the man. 
In regard to the activity of the mosquito at night, for the quarantins purpose above outlined, 
I have to say ihrt in tke report dated May, 1904, of the Yellow Fever Working Perty, Part 2 of 
the Yellow Fever Institute the statement is made (on page 100) in their summary and con- 
clusions thet “ Stegomyia fasciata is a domestic insect. It is most active during the day but 
will bite at night under artificial light.” In another part of this report it is stated that the 
working party noticed that these mosquitoes were especially voiacicus in the morning about 
sunrise. An officer of the service who has bad large experience in localitics infected with yellow 
fever, and especially in the work of eradicating mosquivoes, siates (hat the yellow fever mosquito 
is very active during the twilight. 
As a general rule, the majority of sallors on shore liberty will spend the greater part of their 
time in presumably well Nghted rooms, and if their shore liberty should st-1t at sunset and end 
at sunrise, which times are specified in paragraph 9 of the fruit rezuletions, as the time when 
shore liberty should be denied, said sailors would. in addition to the time above stated, be 
ashore during twilight and sunrise, the times during which the mcsquito ts active without 
artificiel light. In other words paragraph 9 of the fruit regulations does not conflict with the 
opinions that the stegomyia is inactive in the darkness. 
Respectfully, Water WYMAN, 
Surgeon-General. 
““The mission bases itself upon this consideration when it judges it dangerous, in the 
month of January, for the European offictals to return to the town, at least if they are not com- 
pelled to protect themselves at night in an efficient manner against the bites of the Stegompias.” 
+ “ Twice only we have had occasion to observe copulation: tt occurs nearly always at night 
and tn darkness, hence the rarity of observations of this character.” 
