No. G. DEPARTMENT OF AGRICULTURE. 331 



flesh is heir. They muKiply with amazing rapidity and in tliree 

 days a few germs would be capable of produeiug seventy-two bil- 

 li(nis of individuals. This will account for the suddenness with 

 which disease may break out in the human being and, in some in- 

 stances, kill with such rapidity. These low forms of life being so 

 minute, it can be readily understood how they may be carried about 

 by insects. It is calculated that a million of bacteria may rest on the 

 point of a jjin. Therefore a fly could carry many millions of germs 

 on its feet and proboscis. Suppose a person with cholera should 

 vomit GO the street and the ubiquitous, excrement bred house-fly 

 should settle on it and afterward fly into a dining room and rest on 

 food, in all probability the person eating the food would acquire the 

 disease. 



It may be of interest to state what has been discoyered in relation 

 to insects and the deadly bubonic plague of the East. Flies die of 

 the plague and when crushed have disclosed the bacillus or germ of 

 plague in the bodies. These files when crushed and injected into 

 animals produce the plague in the animals. Flies fed with infected 

 mice died with plague. The bacillus of the plague has also been fouud 

 in fleas taken from diseased rats. Insects may transmit disease 

 by transporting the germs upon their bodies and infecting what- 

 ever they alight upon, by inoculating the disease producing or- 

 ganism in biting or stinging. This method is just as certain of 

 producing disease as the sharp needle of the hypodermic syringe is 

 certain of puncturing the skin, providing the person bitten or stung 

 is susceptible. Insects may also distribute disease by means of their 

 excreta and they also serve as intermediate hosts for the develop- 

 ment of the life cycle of certain disease producing organisms. 



Until very recently it was thought that house-flies were essential, 

 as their youog, the maggots, eat a large amount of decaying and 

 waste matter detrimental to the community. If we do away with 

 this material ourselves, Ihe house-fly looses its utility as a scavenger. 

 If these flies distribute the germs of tuberculosis and typhoid fever, 

 as they u«jdoubtedly do, the} are a menace to any community and 

 should be destroyed, or still better, their existence prevented. A 

 female fly will lay about one hundred and twenty eggs and they are 

 nearly always deposited in fresh horse manure. The eggs hatch 

 into maggots in about eight hours and after four days the maggots 

 change into pupae. The pupa state lasts for five days and from it 

 the perfect insect or fly emerges. Thus it will be seen that they go 

 through their total life round inside of ten days and this provides 

 for numerous generations in a summer. While horse manure is the 

 principal food for the young of the lly, they will also feed on spoiled 

 and moist food stuffs, decaying meat, cut melons, dead animals, 

 human excrement, and excrement of poultry. 

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