184 GNATS OR MOSQUITOES — CHAPTER VII 



The length of time required to develop from egg to 

 imago varies greatly ; about a month in Italy, according to 

 Celli, in the case of Anopheles, but usually nmch more 

 rapidly in India. 



In Mr. Aitken's paper, already quoted, he says : "I was 

 anxious to ascertain next the length of the larva life, but 

 found that it varied indefinitely with the conditions. Given 

 warmth and plenty of food a larva will come to maturity in 

 eight days, or perhaps less, but I have had one for more 

 than a fortnight, and then it died before becoming a pupa. 

 The time spent in the pupa state in all my specimens was 

 more than twenty-four, but less than forty-eight hours. So 

 I think we may put down the time which it takes to produce 

 a Mosquito at something between ten days and a fortnight, 

 from the laying of the egg ; and water, treated with kerosine 

 oil once a fortnight, should be perfectly safe. It is very 

 difficult to ascertain the normal life of the adult Mosquito, 

 because we cannot keep them in natural conditions. Some 

 of mine lived for ten days, but, as I have said, they would 

 not lay their eggs, and that alone could not but affect the 

 length of life. . . . To my astonishment I found Anopheles 

 larvae swarming in a dirty drain filled with rotting straw, 

 which gave the water the colour of beer. In May, Colonel 

 Weir sent me two or three bottles of water from other 

 places in Bandora, with Anopheles larvie in them. The 

 breaking of the monsoon, of course, upsets the haunts of all 

 Mosquitoes for a time, but on the 2nd of July I went out to 

 Chinchpoogly and explored the quarries at the foot of the 

 hill, where Dr. Christy told me he had found larvae some 

 time before. I found larvae in many of the pools and one 

 specimen in a little puddle, not more than four inches deep, 

 which must, I am sure, have been as dry as bone ten days 

 before, for we had a long period of hot, sunny weather, as 

 you will remember, in the middle of June." 



This agrees with such scanty observations as I was 

 personally able to make in India, but, owing to the peri- 

 patetic nature of my duties, breeding-out observations were 

 rarely practicable. 



In England, and also in the somewhat similar tempera- 



