56 The Control of Mosquitoes 



the water is near the ground surface, and into 

 which dead grass, sticks, and leaves have fallen. 

 The number of these collections of water is limited. 



HOOF-PRINTS 



The hoof -prints of cows and horses become 

 important Anopheles producers. Riders often 

 take horses over soft ground and in the wet season 

 each hoof-print may become a source of larvae. 

 Cows seem to be particularly fond of walking in 

 soft-bottomed ditches, and remaining at the edges 

 of ponds. In this climate they are not stabled. 

 Where the soil of the pasture is of a soft or clayey 

 character, the foot-prints may be one to six inches 

 or more in depth. These depressions often hold 

 water throughout the wet season, and retain 

 it from showers during the dry season. It is a 

 difficult and expensive task to locate and fill, or 

 treat, all hoof-marks holding water in a large 

 fiat field. The conditions are not improved if 

 such a pasture is subjected to occasional flooding. 

 It has been necessary in some instances to place 

 fences around ponds and portions of pasture lands 

 that become prolific sources of mosquitoes. In a 

 few cases, where wet pasture lands were close to 

 thickly settled suburbs, or villages, it became 

 necessary to have the cattle removed elsewhere. 



