258 MOSQUITOES OF NORTH AMERICA 



ture in the same way as the rate of development of the malarial parasite in the 

 anopheles mosquito.'^ 



The view of Carroll, that the causative organism of yellow fever is a protozoan, 



ultra-microscopic in size and with its life-cycle partly in man and partly in the 



mosquito, has been generally accepted by students of the disease. 



THE YELLOW-FEVER MOSQUITO. 

 DOMESTICITY OF THE YELLOW-FEVER MOSQUITO. 



Aedes calopus is inseparably associated with man in the tropics. It is essen- 

 tially a town mosquito and it is never found at a great distance from habitations. 

 It shows a very decided preference for human blood and must have blood for the 

 development of its eggs. These points were very clearly brought out by Mar- 

 choux, Salimbeni and Simond, of the French commission to Rio de Janeiro, and 

 they have since been verified by many observers. Both sexes inhabit houses and 

 when the requisite conditions obtain the entire life-cycle takes place indoors. 

 This is the only species of mosquito in which the male is attracted to man. 

 Finlay's paper of 1881 shows that he already clearly understood the domestic 

 character of calopus. Ficalbi, in 1896, noted the domesticity and diurnal habits 

 of this mosquito, and that it does not bite at night. Goeldi states that in Para 

 it bites from sunrise until dark. A significant fact is the stealthiness of its 

 attack, always approaching from behind. It retreats upon the slightest alarm 

 but does not relinquish its efforts until it has accomplished its purpose. The 

 ankles and, when one is sitting at a table or desk, the under side of the hands and 

 wrists are the favorite points of attack. Of further significance is the fact that 

 it attacks silently while other mosquitoes announce their presence with the 

 piping or humming note. Doubtless sonifaction has been suppressed in this 

 species in the evolutionary process of adaptation to man. 



On their 1905 joumies many notes were made by both Busck and Knab bear- 

 ing upon the fact that the yellow-fever mosquito has become a strictly domesti- 

 cated species. The hiding habits of the adult, its general air of familiarity with 

 man, its habit of approaching from behind instead of from the front, its extreme 

 wariness, its habit of concealment in garments, working into the pockets and 

 under the coat lapels and collars and of crawling up under the clothes to bite the 

 legs rather than the exposed ankles, are all indications of familiarity with the 

 human species for many generations. 



The habit of hiding, which has just been mentioned, seems very characteristic 

 of this species. It was already noted by Finlay in 1881 and its bearing upon 

 the dissemination of the species pointed out. In houses they will hide in dark 

 corners, under picture moldings, behind the heads of old-fashioned bedsteads 

 and in similar places. They will enter clothes closets and hide in the folds of 

 garments. From this habit, as Finlay states, they are especially apt to be packed 

 with clothing into trunks and carried on journeys. They have been known to 

 emerge alive after some days' confinement of this character. Just how long 

 calopus will live under these conditions has not been determined. 



