THE MOSQUITO 55 



on a diet of bananas and water from two to 

 eight weeks, but it was found essential to keep 

 the atmosphere fairly moist and the food 

 fresh. Grassi found that he could only keep 

 Anopheles alive in his laboratory in Rome 

 for a month. 



Both Anopheles and Culex — at any rate, in 

 captivity — lay their eggs early in the morning. 

 Apparently the nature of the food has some 

 effect upon their fertility, certain observers 

 stating that when male and female are fed 

 on vegetable food alone there is no fertilisation 

 and no oviposition. A diet of blood evidently 

 assists the female to lay her eggs, and perhaps to 

 get them fertilised. One of our female Anopheles 

 laid a batch of 146 eggs, and subsequently 

 laid six more. But, as a rule, a fertilised 

 female does not lay a second batch unless 

 she receives a second meal of blood. The 

 eggs are laid two or three days after the meal. 

 There is also some evidence that a meal 

 of blood is necessary if fertilisation is to 

 be effected. As Austen says in The Report 

 of the Sierra Leone Expedition of the Liver- 

 pool School of Tropical Medicine : — 



The following law is likely to hold good for the 

 Culicidae which feed on man — at least for the common 

 species ; although these gnats can live indefinitely 

 on fruit, the female requires a meal of blood both 

 for fertilisation and for the development of the 



