412 MOSQUITOES OF NOKTH AMEEICA 



success. In his travels through southern Oran (Algeria) in 1892, Mr. Yosseler 

 found a widely distributed species occurring in thousands, not only in the springs 

 of salt or magnesia water in the oases and in the irrigation ditches, but also 

 in the highly polluted, badly smelling pools used to water camels, and in which 

 300 to 400 camels often waded in one day. He found the same species after- 

 ward in pure, fresh water, in hot springs, and in brackish water. He also found 

 that it inhabits the subterraneous waters of the desert and is probably brought 

 up by the boring of artesian wells. One of the officers of the garrison situated 

 in the midst of a salt basin without outlet pointed out to Mr. Vosseler that this 

 little fish eats mosquito larvae, which explained the comparative absence of 

 mosquitoes in that locality. Mr. Vosseler attempted the introduction of these 

 fish into Germany and succeeded very well, in spite of inadequate preparation. 

 They began to lay eggs within a week of their arrival and became accustomed 

 to any animal food. They always prefer mosquito larvae and small crustaceans. 

 The fish in question is Cyprinodon calaritanus. The female is 8 cm. long and the 

 male 5 cm. The eggs are attached singly to water plants or stones at the rate 

 of one or two a day. Mr. Vosseler states that the excellent qualifications of the 

 species are shared by other members of the same family, and in German East 

 Africa at least two genera and five species are known to occur. 



MR. THIBAULT'S OBSERVATIONS. 



In considering the normal relation between mosquitoes and fish, Mr. James 

 K. Thibault, Jr., Scott, Arkansas, in a recent communication presents his views 

 and gives an interesting instance of mosquitoes breeding in the presence of fish, 

 which he considers typical of conditions in some localities : 



" Personally I do not think that mosquitoes ever breed in the presence of fish 

 if the water is open, allowing the fish free access to the larvas, yet it is a matter 

 of common observation that under certain favorable circumstances some species 

 do breed regularly in streams where fish are abundant. Yet even where con- 

 ditions are favorable only a very tew species seem to take advantage of it. So 

 far as my own observations go the only mosquitoes that regularly do so in this 

 locality are Anopheles quadrimaculatus and Culex dbominator. 



" Conditions are favorable where the surface of the water becomes carpeted 

 with aquatic vegetation, which restrains the fish in their movements, yet allows 

 ample room and protection for the larvae of the above-named species. There is 

 a certain deep, slowly running bayou here that is the main breeding place for 

 quadrimaculatus and ahominator at present while two years ago not a larva 

 could be found there at all. The explanation is simple and may be given as a 

 typical example of its kind. Two years ago launches passed through this bayou 

 daily, and all logs and drift were removed as soon as found, so that the water had 

 free passage and the pond weeds found no foothold, except very near the banks 

 where they were completely destroyed by stock. After the launches stopped pass- 

 ing through this bayou, logs soon accumulated and the pond weeds immediately 

 took possession, so that throughout the present season quadrimaculatus and 

 ahominator have bred continuously and abundantly in this bayou. 



" It must be noted in passing that the larvas, pupae, and freshly emerged adults 

 bred in such a location are invariably bright grassy green in color, which gives 

 them additional advantage of the fishes. This is not the case with larvae, 

 etc., found in other places." 



