INSECT FAUNA OF HUMAN EXCREMENT 59J 



Scatella stagnalis Fall. 

 The metamorphoses of the insects of this genus are not known. 

 The flies are found in damp places artd on water plants. The 

 present species is common to Europe and North America and 

 is boreal in its distribution. It is a small fly with mottled 

 wings. Specimens were captured at Washington, May i6, 

 upon a fresh deposit which had been exposed only fifteen min- 

 utes. Two specimens issued August 30, from a deposit of un- 

 known age collected August 18. This record is a novel one. 



Hydrellia formosa Loew. 

 This is an American species which was captured upon an 

 old deposit upon the Potomac Flats near the water, as was 

 quite to be expected since the flies of this genus are most com- 

 monly found upon the leaves of water plants. 



Family BORBORID^. 



This is another group formerly placed in the old family Mus- 

 cidae. The larvae of very few species are known. These are 

 found in dung and in decaying fungi. The little flies of this 

 family, usually black in color, seem to be among the most 

 abundant insects found in this country, not only upon human 

 excreta but upon the dung of other mammalia. In the summer 

 time they almost immediately swarm upon a fresh deposit. 

 They occur very rarely, if at all, in houses. 



Borborus eqtdnus Fall. 

 Insects of this genus are known in Europe to breed in dung, 

 including human faeces, and the flies are recorded by Schiner 

 to be often found in great numbers on human excrement. The 

 species are all rather small and dark-colored and are perhaps 

 the most abundant of the excrement insects. One of the spe- 

 cies of this genus {B. venalicius) was found abundantly in 

 Cuba by Osten Sacken and as it is an African species it is con- 

 sidered probable that it was brought over in slave ships. B. 

 equimcs, like so many of the species which we consider in this 

 connection, is common to both Europe and North America. It 

 varies greatly in size, the largest specimens being five or six 



