INSECTS AS SPREADERS OF DISEASE 403 



relatively expensive, arrangements should be made to screen it 

 so that no flies can reach it ; but screening is very expensive 

 and seldom entirely satisfactory. 



Lime, crude oil, copper sulfate, formaldehyde, and other poison- 

 ous substances have been used in the treatment of garbage and 

 manure to prevent the breeding of flies. But such treatment is in 

 general undesirable, because it makes the manure and garbage worth- 

 less for use as fertilizer, since it prevents also the fermentative action 

 of bacteria, which is necessary to make available the elements of the 

 organic compounds for plant growth. Borax and hellebore can be 

 used so as not to injure the manure. 



Until a community succeeds in eliminating the flies, it is 

 well for every household to protect its own food supply by suit- 

 able screening of the house and by special care in regard to 

 the exposure of food. Every purchaser of food can help by sys- 

 tematically refusing to patronize dealers whose premises harbor 

 flies. And we can all help by keeping our own premises clean 

 and free from these insects. 



