560 HOWARD 



this investigation it was captured in a privy in the Golden Gate 

 Park, San Francisco, CaHfornia, by Dr. A. D. Hopkins, but its 

 occurrence there was probably accidental and the species prob- 

 ably has little or no bearing upon this work. 



Family BIBIONID^. 

 These insects, called by Comstock ' March flies,' are stout 

 flies resembling the fungus gnats in some respects. Their larvae 

 vary in habits, some species feeding on decayed vegetable mat- 

 ter while others attack the roots of growing plants, especially 



grasses. 



Scatofse -pulicaria Loew. 



The flies of this genus breed in decaying vegetable material, 

 in sewers, and human excrement. The present species occurs 

 both in Europe and in this country. In the present work speci- 

 mens were bred June 17 and June 27 from miscellaneous ex- 

 posed fasces collected June 13 and placed ynder cover, and other 

 specimens were captured September 13, at Alexandria, Virginia, 

 in a garden privy. Mr. Coquillett informs me that this species 

 is common on our windows at certain seasons of the year ; but 

 it is not likely to be attracted to any other than foul or decaying 

 matter. 



Family EMPIDID^. 



The flies of this family, sometimes called ' dance flies,' are 

 small or medium sized flies often seen in swarms in the woods 

 flying up and down. The flies are predaceous and also fre- 

 quent flowers. The larvae live in decaying vegetable matter 

 and may be carnivorous. 



Tachydromia species. 

 This genus, of which between 15 and 20 species are known 

 in this country, seems to ])e unknown in its early stages. We 

 have not found the larva, but adults were reared June 27 from 

 the same miscellaneous lot of exposed fasces collected June 13, 

 1899, and placed under cover. 



Rhanifhomyia nianca Coq. 

 The larva; of one European species of this genus are found 

 in the earth. The genus is well represented in the United 



