﻿EXPERIMENTS IN MALARIAL TRANSMISSION. 517 



THE BREEDING OF MOSQUITOES. 

 GENERAL CONSIDERATIONS. 



Most of the species of mosquitoes breed in fresh water; in ponds, 

 sluggish streams, the margins of lakes and swamps or in cisterns, wells, 

 water tanks and all other receptacles for collecting water around houses, 

 which are not covered by wire gauze or other mosquito-proof covering. 

 Certain species breed only in open meadow or marsh waters, others only 

 in Avoodland waters and again others only in receptacles in or near houses. 

 Examples, respectively, of these three classes in the Philippines are 

 Nyssorhynchus barbirostris Vander Wulp, Desvoidya fusca Theob., Wor- 

 cesteria grata Banks, Gulex fatigans Wied., and Stegomyia persistans 

 Banks. The total number of known species of Culicida? found to breed 

 in salt or even brackish water is so very small that the finding of a true 

 anopheline breeding under such conditions is remarkable. 



Only the following species of Culex are known to multiply in salt or 

 brackish waters in the United States : C. solicitans Walk., C. salinarius 

 Coq., C. tceniorhynchus Wied., and C. cantator Coq. In Europe Bancroft 

 and Ficalli record larvae of Culex salinus Fie, from salt water, while 

 Theobald adds Culex marinus Theob. 



Three species of mosquitoes have been found breeding in salt water in 

 the Philippine Islands ; they are Culex microannulatus Theob., Myzomyia 

 ludlowii Theob., and Culex sp. indet. In a former publication 2 I stated 

 that C. microannulatus Theob., breeds in brackish water, but it has since 

 been found in the same places as M. ludlowii Theob.; that is, in water 

 which upon analysis yields a greater percentage of salt than that of 

 Manila Bay. Myzomyia ludlowii Theobald was the species used in the 

 transmission of malarial parasites in the series of experiments recorded 

 in this paper. It is quite evident from collections made in the various 

 parts of the Philippine Islands, that this species is quite generally distrib- 

 uted. It has been taken in Pampanga Province, in Jolo, Panay, Negros, 

 Cebu, Manila, Cavite and Mindoro, so that its range is probably general 

 in this Archipelago. It is always found in what we might term tidal 

 backwaters, namely in swampy regions where the incoming tide floods 

 considerable areas intersected by channels and dikes. In these places 

 a certain amount of water is left by the outgoing tide, and as evaporation 

 takes place, the remaining water becomes more salty until the next tide, 

 when it is once more restored to nearly its ordinary specific gravity. 



The amount of rain during the season when these mosquitoes are 

 most abundant, namely from November to July, is not sufficient to render 

 the water which remains in their breeding places sufficiently fresh to 

 injure or destroy the plant life upon which the mosquitoes feed, or to 

 be detrimental to the insects themselves ; on the other hand it has been 



-This Journal (1906), 1, 988. 



