132 



bottles, as previously described (p. 91), and allowed to 

 lay their eggs. 



If care is taken to place only one species in a 

 bottle, the characters of the ovum may be noted, in 

 addition to the adult insect. 



Some of the ova should be placed in fresh water, 

 and an attempt made to determine the characters of 

 the larva when it has hatched out and is sufficiently 

 grown. 



2. Breeding out. Full-grown larvae, and especi- 

 ally nymphae, are collected. These are collected from 

 every possible source. Scarcely any water in the 

 tropics will be found free from some form of mosquito 

 larvae. Even strongly brackish waters, containing 

 over one per cent, of salt, often contain large numbers. 



Examine water from the following sources: 



(i) Domestic utensils, cisterns, tins, pots, cala- 

 bashes, boats, etc., in which there has been water for 

 three or four days. The larvae of Stegomyia, Culex, 

 etc., and only rarely Anophelines, will be found. 



(ii) Cess pits, pools full of decaying leaves, etc., 

 sewage ditches. Note larvae of certain species of 

 Culex, etc. 



(iii) Observe presence of the larvae of Stegomyia 

 and Culex in the water which collects in the axils of 

 banana leaves and other plants. Also, occasionally, 

 Anopkelines in large collections of water of this kind. 



(iv) Puddles of all kinds, with and without algae, 

 ponds, tanks, swamps, rice fields, ditches, canals, 

 rivers, streams, lake margins, and wells, and observe 

 that in all, Anopheline, as well as Culicine larvae, may 

 abound. 



Note that in waters covered with certain species 

 of Lemna (duck- weed), Ano-phelines are rarely found. 



(v) Examine the larvae (p. 190) and roughly 



