June, 1909.] 



Miscellaneous Pests. 



Feeding Habits of Millions. 



Millions feed on mosqnitos and on 

 many other small forms of animal life 

 which occur in the waters they inhabit. 

 When they are kept in captivity, how- 

 ever, it is sometimes difficult to provide 

 a snfS'-'ient amount of the natuial food. 

 It has been found that at such times 

 they will eat certain kinds of plant lice, 

 red spider, and the eggs and young of 

 scale insects. 



It has been found that the plant lice 

 which occur on certain plants will not be 

 eaten by millions, as also some kinds of 

 scale insects. The kinds of plant lice 

 and scale insects that millions will feed 

 upon can easily be ascertained by ex- 

 periment in a glass jar. 



Hard-boiled eggs, chopped very fine, 

 will be found a useful food also, while 

 corn (maize) meal will be eaten by the 

 fish if they are very hungry. 



Millions are among the most active of 

 all the natural enemies of mosquitos, and 

 they live in many of the situations in 

 which the Anopheles mosquito breeds. 

 There is, therefore, every reason to 

 suppose that in any malarial district 

 there would be a decrease in the numbers 

 of Anopheles mosquitos if millions could 

 be successfully introduced, more especi- 

 ally if they attacked the Amopheles as 

 actively as they do the other species 

 already mentioned. 



The millions are very persistent. A 

 very small fish will attack a large full- 

 grown larva, and, failing to capture it 

 at the first attempt, vill follow it up for 

 repeated trials until success attends its 

 efforts. This has been observed in an 

 aquarium jar, where it has also been 

 noted that even when gorged to disten- 

 tion, the millions will continue to make 

 frantic efforts to catch more and more 

 of this larvse, until they are unable to 

 swallow the latest capture. A fish hold- 

 ing a large mosquito larva in its mouth 

 until some of the food already swallowed 

 can be digested is not an unusual sight. 

 The captured larva, it will be observed, 

 is gradually swallowed, as room is made 

 to receive it. 



As an experiment, a garden tub was 

 made ready for aquatic plants, and 

 some ten days elapsed after the tub was 

 filled before millions were put into it, 

 and the water became literally alive 

 with mosquitos. It was feared that the 

 few millions which were put into the 

 water would not be able to destroy all 

 the mosquitos before they should have 

 time to finish their development. Accord- 

 ingly, a small quantity of kerosene was 

 thrown on the surface of the water in 

 order to kill off the larger number of 

 mosquitos, and thus leave to the millions 



merely the task of keeping the water 

 free from any fresh invasion by mos- 

 quitos. During the first week after the 

 introduction of millions into this tub a 

 few mosquito larvae were to be seen in 

 the water, but during the next six 

 months none were seen when the water 

 was examined. 



In another instance, a number of 

 millions were kept in a jar in the labor- 

 atory of the Imperial Department of 

 Agriculture. They had been several 

 days without food when a collection of 

 living mosquito larvse was brought 

 in from a stagnant roadside pool. As 

 these larvae were introduced into the 

 aquarium they were attacked vigour- 

 ously and persistently by the fish, who 

 fed until gorged. 



There can be no doubt that millions 

 are very efficient as natural enemies of 

 the mosquito, and in Barbados they have 

 been observed to eat the eggs, larvae, and 

 pupae of both Culex and Stegomyia. 



Introduction op Millions to 

 New Localities, 

 The Imperial Department of Agri- 

 culture introduced millions into St. 

 Kitt's-Neyis and Antigua in 1905, into 

 Jamaica in 1906. and more recently, in 

 1908, into St. Vincent, St. Lucia, and 

 Guayaquil. These fish have also been 

 taken to British Guiana, Colon, and 

 Bolivar. 



In August, 1905, a number of millions 

 were sent to Antigua in a kerosene tin. 

 They arrived in good condition and 

 were kept in a tank at the Botanic 

 Station until they had increased suffici- 

 ently to be distributed without weaken- 

 ing the source of supply. The fish were 

 liberated in several ponds and streams, 

 and flourished so well that the Country 

 Board of Health undertook the work of 

 stocking all the ponds and streams of 

 the island. At the present time, about 

 three years from the first introduction- 

 all the more or less permanent water of 

 that island is stocked, and many planters 

 and others have commented on the 

 apparent abatement of the mosquito 

 nuisance in many localities. 



In August, 1905, millions were sent to 

 St, Kitt's also, where they flourished 

 equally well as at Antigua. Many 

 streams and ponds have been stocked, 

 but the distribution of the fish has not 

 been taken up by the local Government 

 in the same way as at Antigua. 



In Jamaica, to which place they were 

 sent by this Department in 1906, millions 

 have been established, with an abate- 

 ment of ' fever ' in places. 



The idea of stocking ponds, lakes, and 

 streams with fish in order to keep down 



