X] BIONOMICS 171 



According to Marchoux, who has given one of the most 

 complete accounts of 5. fasciata, the female is entirely nocturnal 

 in its blood-sucking habits, except for a short time after it 

 emerges from the pupal case. Under these latter conditions 

 the insect is so hungry that as soon as it is able to ily it sets 

 off to find a host. Once having succeeded in obtaining a meal, 

 the female comes to rest in some dark corner, and in future 

 only attempts to feed towards the evening, or at night. This 

 statement, however, as to the nocturnal feeding habits of 

 5. fasciata has been denied by many subsequent investigators, 

 who agree in the view that this mosquito is mainly diurnal in 

 its feeding habits. Although in nature blood appears to be the 

 only food of the females, Goeldi succeeded in keeping them alive 

 for more than three months on a diet of honey. These insects, 

 however, were unable to lay any eggs. 



Length of life. In a state of captivity, female 5. fasciata 

 have been kept alive for a period of more than four months, 

 so that their duration of life is comparatively long, but in 

 nature, it is doubtful whether an insect would often be able 

 to live such a long time. The occurrence of isolated cases of 

 yellow fever long after an epidemic has ceased may be due 

 to the persistence of infected mosquitoes or, on the other 

 hand, to the presence of mild and unrecognized cases of the 

 disease. 



The male has a much shorter life than the female, for 

 as it feeds on the nectar of flowers, and moreover is very active, 

 it requires to feed much oftener. As a result of its continual 

 search for nourishment, and also for females, the male is con- 

 tinually exposed to accidents and soon loses his protective 

 scales. From this moment the slightest drop of moisture is 

 sufficient to cause the suffocation of the insect. 



The maximum period that female 5. fasciata have been 

 kept alive when nourished on honey is 102 days, whilst under 

 similar circumstances males only lived for periods varying 

 from 28 to 72 days. 



Fertilization and egg-laying. Copulation is usually accom- 

 plished in the open air, especially during the warm hours of 

 the day. The union is made when the insects are flying, only 



