162 PROCEEDINGS OF THIRTY-SIXTH FRUIT-GROWERS ' CONVENTION. 



house as does the blowfly (Calliphora vomitoria), and therefore rarely 

 attacking the prepared foods of man. We have now pointed out the 

 qualities of a good natural scavenger, namely, it must do its work 

 effectively and it must not enter the dwellings of man to attack his 

 foods prepared for use. Certainly, this does not apply to the common 

 house fly. 



The annihilation of a species whether complete or relative always 

 brings opposition. Few ideas are more firmly rooted in the mind of 

 the average man or woman than that Nature has brought forth nothing 

 that is useless in the economy of the human family — it must be good 

 for something, otherwise it would not be in existence and should there- 

 fore not be exterminated nor even molested. True it is that we must 

 study Nature's ways and endeavor to find out what she is trying to 

 do, then help her to carry out her plans more quickly and more accu- 

 rately. For instance, if Nature has provided scavengers, she is endeavor- 

 ing to clean up, thus pointing out to man what he should do. The 

 house fly is often spoken of as one of Nature's scavengers. By a care- 

 ful study of the performance of this function by the fly, it can be 

 said without question that the house fly is a poor scavenger and it 

 certainly does not stay out-of-doors. The house fly breeds primarily 

 in excrementitious matter, and this of all offal from animals and man is 

 the most dangerous source of infection. Thus all evidence is against 

 the house fly, and certainly no one would suggest that the house fly be 

 left unmolested, because it helps man to keep his premises clean (which 

 it does not), and that which the fly might be liable to reduce a little 

 should not be permitted to accumulate exposedly on the basis of ordi- 

 nary rules of sanitation. 



THE HOUSE FLY AS A CARRIER OF DISEASE. 



It may be said without hesitation that the house fly is one of the 

 most dangerous animals, the greatest menace to human health. It is 

 so, largely because it is generally regarded as an innocent creature, 

 and because the labeled disease in large parcels is not observed, of 

 course, there is no evidence. There is more first class experimental 

 evidence against the fly to-day than there is against any other insect, 

 except the mosquito. The fly is dangerous because of its vile breeding 

 and feeding habits, during which time it may become loaded with dis- 

 ease producing organisms. The mouthparts and feet are perfect col- 

 lectors of filth. Each one of the six feet is equally fitted with bristles 

 and hairy pads which secrete a sticky material, adding thus to their 

 collecting powers. The diseases which it is possible for the house fly 

 to transmit and which have been proven against it are typhoid fever, 

 dysentery, summer diarrhea in infants, cholera, tuberculosis, hospital 

 gangrene, and several other disease for which the evidence is as yet 

 meager. Now the causative organisms ("germs") of the above men- 

 tioned diseases are found in the excrement, vomit, sputum, and pus. all of 

 which form articles of diet for the fly, and the mode of infection is 

 by way of human food (wounds in the latter case) which are con- 

 taminated, or infection of wounds and cuts in gangrene. Time alone 

 prevents us from dwelling on the details of infection. 



From 75 to 125 eggs are deposited in one mass, and there are usually 

 several (2 to 4) such layings. The eggs hatch in from twelve to 



