THE MALARIAL MOSQUITOES 109 



Natural Breeding- Places of Aiioplieles. 



A number of the natural breeding-places of Anopheles 

 niacuUjiennis and A. pmictqicnnit^ have been found by the 

 writer in the United States. They have always been found 

 in more or less permanent pools of water, either in the bed 

 of an old canal or in spring-fed woodland streams, or in 

 the side pools or shallows of field spring-s, or in artificial 

 excavations filled with surface water. In such places, 

 when supplied with a certain amount of green scum, the 

 little larvje will often be found resting at the surface of 

 the water, and occasionally darting from one spot to 

 another. 



The larvae of A. j^uit^ctijwinis ditier from those of A. tiia- 

 culipennis largely in the marking of the head, as indicated 

 in the accompanying figure. Tlie temperature of the 

 water which they inhabit varies from 18° C. to 25° C- 

 Nuttall and Shipley state that in England these larvae 

 are to be found in pools, ditches, backwaters of rivers 

 and canals, and in other slow-flowing waters ; almost in- 

 variably in such waters as are clear and very rarely in im- 

 l^ure or brackish water. In their experience, they jjrefer 

 pools which are not shaded by trees, althougli I have 

 found them in this country on several occasions in a 

 dense shade. They are very rarely found in water con- 

 tained in barrels and troughs and fountain basins, and 

 they are very rarely found in the same water with the 

 larva) of Culex. Mr. E. E. Austin, in " The Eeport of 

 the Proceedings of the Expedition for the Study of the 



