NATURAL REMEDIES. 119 



birds can be adopted for the purpose of destroying mos- 

 (piito larvae in ponds, rain pools, etc., near houses, and in 

 ponds in well cleared fields, rolling and cultivated land, 

 where there is no extent of wood and management of the 

 fowl can be made simple and their breeding profitable; 

 and fish can be introduced in our public lakes. In these 

 different provinces the different agents of this compound 

 remedy will effect beneficial changes. It has been ob- 

 served by myself how infrequent the larvfe are in the 

 Central Park (jSTcw York City) lakes, and that their ab- 

 sence is due to the industry of the fish and water fowl, 

 though there is another suspected cause which I will men- 

 tion in a succeeding section. 



The obvious dissatisfaction over these remedies is their 

 probable insufficiency ; but as helpful and useful, in the 

 absence of more perfect means, there is in my mind no 

 doubt. 



Third, this group of natural remedies comprises the dis- 

 semination of parasitic fungus and the cultivation of fresh 

 water algae to such an extent as to prevent or retard the 

 development and health of the mosquito larvae. Dr. 

 Hagen calls the attention of entomologists to the use of 

 beer yeast for destroying greenhouse pests, which proved 

 to be successful against plant lice (aphidae) and potato 

 beetles. But as this process is so uncertain to use against 

 the mosquito, I only suggest that experiments in this di- 

 rection may be made for the observation and record of 

 facts which may lead to results which are of practical use- 

 fulness. 



Mr. L. P. Gratacap, of the American jNIuseum of Natu- 

 ral History, has suggested that the increase of fresh water 

 algae would greatly impede the progress of the mosquito 



