INSECT FAUNA OF IIUIMAN EXCREMENT 57 1 



Down to the summer of 1899 we had been unable to breed a 

 house fly from any other substance than horse manure. In the 

 summer of 1898, while the concentration camp talk was in full 

 blast, efforts were made to ascertain to what extent, even vmder 

 abnormal circumstances, house flies would be attracted to or 

 could be induced to breed in human excrement. Large earthen 

 boxes were prepared with a gauze covering supported upon 

 upright corner posts, making an enclosure with a cubic content 

 of about twenty-seven feet. In these was placed freshly depos- 

 ited excrement, and in it were liberated upon a number of oc- 

 casions from one hundred to two hundred house flies. Not 

 more than ten percent of the flies paid any attention to the 

 excrement ; about this percentage settled upon it and sucked up 

 the moisture, flying away after a short interval. In not a single 

 case was an egg deposited. This series of observations seemed 

 very significant to the writer, and after they were concluded he 

 was quite inclined to doubt the extensive breeding under any 

 conditions of the house fly in human excrement. The erro- 

 neousness of this partly formed conclusion, however, was plainly 

 shown the following summer, that of 1899. I had become 

 convinced of the desirability of the most exact work upon this 

 question, and elaborate observations were made, extending 

 throughout the entire summer, the result being that it was shown 

 beyond a doubt that the house fly may and does visit human 

 excrement when fresh, and that it may and does oviposit in it, 

 and that it may and does breed successfully in this substance. 

 I am inclined to believe that what may be termed the psycholo- 

 gical influence of confinement, even in so large an enclosure as 

 the one used in the 1898 experiments, alarmed the flies, caused 

 their early death, and prevented them from obeying their natural 

 instincts and performing their natural functions. I recalled a 

 similar effect upon the honey bee when enclosed in numbers un- 

 der a gauze netting covering a large plant and containing perhaps 

 fifty cubic feet of space. In that case also all of the bees died in 

 a few hours. Therefore, in the summer of 1899 another line of 

 experimentation was chosen. Human excrement was exposed 

 under differing conditions in different parts of the surrounding 

 country for a certain space of time and was then collected and 



