PEOGEESS IX BIOLOGICAL IXQUIEIES, 1921, 17 



■was that the top minnow. Gamhusia afinis^ was very widely employed 

 as an agent in the control of malaria. A report of observations made 

 b}^ Mr. Hildebrand during this campaign has been published bj^ the 

 Public Health Service.® 



The latter part of the season was devoted to investigations at Sa- 

 vannah, (ra.. where a special effort was made to determine the relative 

 value as eradicators of mosquito larvae of two other American vivipa- 

 rous species of fishes, II etc rand ria fonyiom- and Mollienhw Jatipinna^ 

 both of which are abundant at Savannah. It was demonstrated that 

 Ileterniulria formo^a is of real value and is well woi'th careful con- 

 sideration Avherever it occurs. MoU'ienisia latipinrM^ on the other 

 hand, appeared to be practically worthless. 



The antimalaria campaigns in the various States were brought to 

 a close early in November, in which month the annual meeting of the 

 National Malaria Committee and the conference of sanitai-y engi- 

 neers engaged in antimalaria work took i)lace in Louisville, Ky., 

 where the outcome of the past season's campaign was reported and 

 discussed. The subject of mosquito control by the use of top min- 

 nows received extended discussion, and the fact was brought out that 

 nearly every sanitary engineer had made use of (rumhusia affinis as 

 an agent in malaria control with excellent results. The saving of 

 large sums of money was reported, because fish control replaced other 

 methods at much less expense. 



Similar advisory work was done by Mr. Hildebrand in the spring 

 of 1921 before establishing headtjuarters at Augusta, Ga., for further 

 investigations to determine more fully the conditions of effectiveness 

 in the employment of fish for destruction of disease-bearing mos- 

 quitoes. 



CONDITIONS GOVERNING Ar.rNnANCE OF :MOSQr ITO-DKSTHOYING FISH. 



R. L. Barney and Barry Anson have continued the ornjanization 

 and summarizing of data collected at Mound. La., wliere imestiga- 

 tions of the use of fish for control of nioscjuito breeding were pre- 

 viously con(hicted in r-oojx'ration with the Bui'cau of Entomology. 



Reports^ printed outside the Bureau's i)ublications demonstrate 

 the varying seasonal frecjuency of (iambusia, the mosquito-eating 

 fish ; the seasonal variation in the proportions of the sexes and its 

 bearing on the abun(hince of the species in nature: the effect of en- 

 vironment on the abundance of the species; and the relation of plants 

 of varying hal)its of growth to oxygen su|)ply and to the capacity of 

 small ponds to support the top-minnow (iambusia. Furlhcr obser- 

 vations have been made on the seasonal abundance of (iambusia, es- 

 pecially in relation to the fecundity of the species. Ajtpi-opriate con- 

 sideration has l)een gi\en certain points concerning the anatomy of 

 the female reproductive organs of this fish. 



• Hildohrand, Samuel P.: Top Minnows in Rilation to Malaria Control. With Notes on 

 Thoir Mablls and Dlstrihiition. Treasury Df-partment, Public Health Kulletin No. 114, 

 Ma.v, l!»ijl, :i4, II. Washington. 



' Harni'}', It. Ij., and AiiHon, V,. ,1. : Itelation of Certain .Aqnalic Plants to Ox.vgin Supply 

 and to Capacity of Small Ponds t<> Support the Toii-minnow {(htiuhuHUi afjliiia). Trans- 

 artlong, American FlshirieK Society, l!»'j(». pp. 20.H-1'7H. 



Aliundaiice of tlU' Mriscpilto I>estroyinff Top-iuiniiow (himhiisid affiniH, 



P'Hpeelaily in It<lation to Male Frequency, Ecology, Vol. II, No. 1, January, lUiil, pp. 



69869°— 22 ". 



