162 Journal of the Mitchell Society [Ma)'ch 



rious sections of tlie Soutli where it inliabits i)()tential inosqiiito-hreed- 

 iiig areas. It is not limited for food entirely to live animals, but it 

 undoubtedly prefers that kind of a diet, and a wiggle tail certainly 

 is a "bait" of suitable size for this fish and one which appears to 

 "tickle the palate." The habit of surface swimming which is corre- 

 lated with surface feeding in Gamhusia is highly developed, the fish 

 having received its common name, "Top Minnow," because of its 

 almost constant appearance at the surface of the water. 



Gamtiisia is viviparous, i. e., the eggs are fertilized and hatched 

 within the body of the parent fish, and the young when born are from 

 8 to 10 mm. (-^g to % in.^ long and come into the world well 

 developed, being much better able to take care of themselves than most 

 fishes hatched from eggs in the more usual way. This fish, unlike 

 most others, therefore, requires no special environment for depositing 

 and hatching eggs, the young being born as the female moves about in 

 the water. The species, for this reason, is able to reproduce under a 

 very wide range of conditions. The young come in broods, numbering 

 from a few to one hundred or more, throughout the summer and at 

 intervals of from three to several weeks each. The young when born 

 are so well developed and so thoroughly capable of beginning an inde- 

 pendent existence that their chances for survival are excellent. They 

 grow rapidl^^ and the early broods of the season become sexually ma- 

 ture and themselves have young before the end of the summer during 

 which they are born. Multiplication therefore is very rapid. 



Gamhusia, as already indicated, is common in most of the mala- 

 rious sections of the South and in many localities it has become dis- 

 tributed to the sluggish ditches and standing bodies of water, as far 

 as natural waterways have from time to time been open. In other 

 localities the fish is not so universally distributed and in nearly every 

 vicinity there are present some waters which the fish is unable to 

 reach because there are no channels connecting them with other bodies 

 of water. It is here where aid in distribution by man is needed. 



It is not claimed that Gamhushi, when present in a body of water, 

 will eliminate all mosquito production under all conditions. Some- 

 times, when conditions are proper and sufficient top minnows are 

 present, mosquito production is completely eliminated. In many 

 cases it is not eliminated but very greatly reduced. 



The value of Gamhusia as an eradicator of the immature mosquito 



