322 



THE AGRICULTURAL NEWS. 



October 



1916. 



'(certain Acacia spp. were found to be suitable trees) 

 and on these the arsenite of soda bait was exposed in 

 strategic situations, i.e. over manure heaps or other 

 breeding places, in and around buildings or anywhere 

 ■where flies tend to congregate. 



Experiments conducted at various centres gave 

 very satisfactory results. Reduction in the number of 

 flies was apparent at the start. This method of fly 

 destruction indeed proved to be so successful that it 

 ihas been systematically taken up by the municipal 

 authorities in Capetown and by the South African 

 Army Medical Corps authorities. 



The important principle to bear in mind is the 

 idea of attracting the flies to their breeding places and 

 killing them there before they gain entrance into the 

 house. Thus the duty of fly destruction falls upon 

 lihose who are responsible for the accumulation of 

 manure or refuse, and not upon the householder who 

 at present wages a more or less ineffective campaign 

 indoors with fly-paper and similar contrivances. 



In connexion with the manure heap, there is 

 ■still another method that might be followed. Refer- 

 ence to the last issue of the Agricultural News 

 -(p. .314) will show that it has been found possible to 

 destroy the larvae of the domestic fly by merely turning 

 the inner parts of the jjile over the fresh manure which 

 •contains larvae. The heat generated by the manure, 

 as well as the gases whioh are formed during ferment- 

 .ation are very fixtal to the larvae when they are 

 exposed to them. The simplicity of this method of 

 ■ control renders it of considerable practical importance, 

 and it should be employed in conjunction with the 

 use of the poison bait described above. 



Several observations of interest have been made 

 •concerning fly breeding and manure constituents. In 

 South Africa it was noticed that numerous flies 

 apparently feed on certain .specks on the straw and 

 coarse litter in the manure. On close observation 

 it was found that the surface of this straw was suffi- 

 ciently smooth and hard to serve as a bait-carrier. 

 It was therefore decided to vary the method described 

 above and sprinkle the bait lightly over the manure 

 itself This was accompanied by satisfactory results, 

 but it was not found advisable to dispense with the 

 leaf carriers. 



Other observations have been made in Paris* 

 ■with the obiect of determining the constituents of 



i ■*£. Rouband, ItiUrnal tonal Review of the Science and 

 FracHce of AgticnH" ", Vo;>,v VII, No. 2, p. 188. 



horse manure favourable to the deposition of eggs. 

 Eggs do not appear to be deposited in the unmixed 

 dung and urine-soaked litter of cattle, goats and pigs. 

 These excreta, however, may become suitable material 

 for the development of flies after the addition of such 

 a secondary fermenting substance as wheat bran. 

 Mixing cow and horse excreta, and feeding wheat bran 

 to animals render the resulting manure liable to 

 infestation by larvae. 



The foregoing information embraces the principal 

 facts known regarding the control of fly breeding in the 

 refuse and manure heap. We may now say a few 

 words in connexion with the sanitary side of the ques- 

 tion of fly control with a view of emphasizing its 

 importance. Reference to the house-fly merely as 

 a nuisance is inadequate, for, the domestic fly, like the 

 mosquito, is more than a nuisance — it is a source of 

 danger for it carries the germs of disease. The dissem- 

 ination of typhoid is largely attributed to flies, and in 

 this connexion it is important to prevent flies obtain- 

 ing access to milk, which forms an excellent culture 

 medium for most pathogenic organisms. Flies, there- 

 fore, are particularly dangerous in the vicinity of dairy 

 cows, and under these conditions the employment of the 

 poison bait method of control should be systematic. 

 Another disease the transmittal of which is credited to 

 the house-fly, is infantile paralysis. In this disease the 

 patient exhibits a discharge from the mucous mem- 

 brane of the nose and flies, if not screened, tend to 

 settle and then disperse with the infection to 

 another person who may be healthy. In New York 

 this is believed to be the principal form of dissemination 

 during the epidemics of infantile paralysis that some- 

 times occur in that city. 



Besides the house-fly, the manure heap breeds, 

 as already stated, the dangerous stable fly, Stovi- 

 oxys calcitrans, which carries the fatal equine 

 disease 'Mai de Caderas'. This disease broke out 

 a year or two ago in British CJuiana; it is com- 

 mon throughout South America. This affords addi- 

 tional evidence of the obligation of the agiiculturist 

 and stock breeder in the matter of controlling flies 

 along the lines laid down in this article. It should 

 be remembered finally that flies are able to travel 

 quite long distances; the dispersion of marked flies over 

 an area of from -5 to more than 12 square miles has 

 been observed. Thus the manure heap is not only 

 a source of danger and annoyance to the immediate 

 neighbourhood but to a much larger territory as 

 indicated by the observation just quoted. 



