184 The Philippine Journal of Science i9i7 



cannot be regarded as conclusive, as the fish might act very 

 differently under natural conditions. Therefore the following 

 experiments conducted in open ponds are probably of greater 

 value. 



Located near the Bureau of Science are five fresh-water ponds 

 used for fish cultural work. They range in size from 2 by 12 

 to 29 by 39 meters and from 0.5 to 1 meter in depth. Grass 

 and sedges grow along the margins. 



Two hundred mosquito fish were placed in the large pond. 

 This pond was already well stocked with adult black bass, Mi- 

 cropterus salmonoides Linnaeus and also contained a number 

 of native fishes, such as dalag (Ophiocephalus striatus Bloch) 

 and ayungin (Therapon argenteus Cuvier and Valenciens). 

 The object of the experiment was to ascertain if mosquito fish 

 could maintain themselves and multiply in a body of water 

 stocked with these voracious fishes. 



The results have been most satisfactory, for the mosquito 

 fish not only maintained themselves and kept the pond free from 

 mosquitoes, but during the past two years have increased to 

 many thousands. Two thousand five hundred mosquito fish have 

 been taken from this pond and planted in streams and swamps 

 in the vicinity of Manila, without making any appreciable in- 

 road on the supply. 



One of the small ponds, kept as a control without any mosquito 

 fish, soon became infested with larvse. 



From the original stock of 24 mosquito fish, brought to Manila 

 in 1912, the Bureau of Science has distributed over 7,610 mos- 

 quito fish in the streams and swamps of the Philippines. While 

 the fish are as yet too few to make any appreciable difference 

 in the number of mosquitoes, there can be but little doubt that 

 in a few years they will materially decrease the number of these 

 pests and greatly assist in eliminating malaria from the Islands. 



SHORT REVIEWS OF THE LITERATURE ON MOSQUITO DESTRUCTION 

 EXAMINED BY THE AUTHOR 



Howard, Leland Ossian. Notes on the mosquitoes of the United States 

 giving some account of their structure and biology, with remarks on 

 remedies. Bull. U. S. Dept. Agr., Div. Ent. new. ser. (1900), No. 25. 

 This publication gives an account of the structure, life histories, and 

 distribution of the mosquitoes of the United States and Alaska. Various 

 methods for the destruction of these pests are given. The author recom- 

 mends the introduction of fishes into their breeding places. 

 Idem. Mosquitoes; how they live; how they carry disease; how they are 

 classified; how they may be destroyed. New York, McClure, Phillips 

 & Co. (1902). 



