268 MOSQUITOES OF NORTH AMERICA 



Simond, Aubert and Noc, in their work on the epidemic of yellow fever iu 

 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 caloims during the hot months, they 

 fomiulate this doctrine as follows : " C'est en se basant sur cette consideration 

 que la mission estiraa dangereux, au mois de Janvier, le retour des fonctionnaires 

 europeens dans la ville, a moins qu'ils ne fussent astreints a se proteger la nuit 

 d'une maniere efficace contre les piqures de Stegomyias." * This is a complete 

 inversion of biological facts. Aedes 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 

 I'occasion d'observer I'accouplement : il a lieu presque toujours dans la nuit et 

 a I'ohscurite, d'ou la rarete des observations de ce genre." f 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 vemos 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 contracting 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 " 



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 Aedes 

 calopus bites only at night. It was therefore decided to make inquiry of the head of the 

 Public Health and Marine Hospital Sei-vice and in reply we received the following letter : 



Treasury Department, Washington, January 26, 1911. 

 Dr. L. O. Howard, 



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 and sunrise, 

 he cannot conveniently 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 quarantine purpose above outlined, 

 I have to say that in the report dated May, 1904. of the Yellow Fever Working Party, Part 2 of 

 the Yellow Fever Institute the statement is made (on page 100) in their summary and con- 

 clusions that " 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 voracious in the morning about 

 sunrise. An officer of the service who has had large experience in localities infected with yellow 

 fever, and especially in the work of eradicating mosquitoes, states that the yellow fever mosquito 

 is very active during the twilight. 



As a general rule, the majority of sailors on shore liberty will spend the greater part of their 

 time in presumably well lighted rooms, and if their shore liberty should start at sunset and end 

 at sunrise, which times are specified in paragraph 9 of the fruit regulations, as the time when 

 shore liberty should be denied, said sailors would, in addition to the time aliove stated, be 

 ashore during twilight and sunrise, the times during which the mosquito is active without 

 artificial light. In other words parngraph of the fruit regulations does not conflict with the 

 opinions that the stegomyia is inactive in the darkness. 



Respectfully, Walter Wyman, 



Surgeon-General. 



* " The mission bases itself upon this consideration when it judges it dangerous, in the 

 month of January, for the European officials 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 Stegomyias." 



t " Twice only we have had occasion to observe copulation : it occurs nearly always at night 

 and in darkness, hence the rarity of observations of this character." 



