222 



MOSQ UI TO ERA DICA TION 



Fig. 145. — Making a concrete privy-vault mosquito-proof. All cracks are 



plastered over. 



(Photo by E. H. Magoon, C. E.) 

 Fig. 146. — While this pond was free from mosquito larvae, owing to the 

 activities of Gambusia, there was abundant breeding in the barrel which the fish 

 were unable to enter. 



