APPENDIX II 

 On Some Flies Reared from Cow Manure* 



IN the summer of 1889, while engaged in an investi- 

 gation of the habits and Hfe history of the horn fly 

 of cattle (Hcematobia serrata), the writer at various 

 times brought to Washington, from different points 

 in Virginia, large quantities of cow manure collected 

 in the field, and eventually succeeded in working out 

 the complete life history of the horn fly, as displayed 

 in Insect Life, Vol. II, No. 4, October, 1889. In this 

 article the statement is made, in concluding, that the 

 observations were greatly hindered and rendered dif- 

 ficult by the fact that fresh cow dung is the nidus for 

 a number of species of Diptera, some about the same 

 size and general appearance as the horn fly, and that 

 no less than twenty distinct species of flies had been 

 reared from horse and cow dung, mainly the latter, 

 and six species of parasitic insects as well. The plan 

 finally adopted of securing the isolation of the horn 

 flies was to remove the eggs from the surface of the 

 dung and place them with dung which was absolutely 

 fresh and collected practically as it fell from the cow. 

 A report upon the other species was promised, but was 

 never published, although Professor Riley, in his re- 



♦Reprinted from an article with this title, by L. O. Howard, 

 published in the Canadian Entomologist, Vol 33(1901), pp. 42-44. 



281 



