INSECT FAUNA OF HUMAN EXCREMENT 547 



of Diptera mentioned ; Mr. Schwarz named the Coleoptera, and 

 Mr. Ashmead named the Hymenoptera. To Mr. Pratt more 

 than to any one else is due the large amount of material studied. 

 Undeterred by the extremely disagreeable nature of the "in- 

 vestigation and with a rare enthusiasm, he devoted himself in- 

 defatigably to the work during the summer of 1899, making 

 collections and conducting rearing experiments. In the autumn 

 Mr. Pratt developed a severe case of typhoid fever and was 

 confined in the hospital for more than six weeks. This fact 

 may be coincidental but it is possible also that the fever 

 may have been contracted as a result of his investigations. 

 Messrs. Banks and Busck also collected a certain amount of 

 interesting material, and Dr. A. D. Hopkins, while engaged on 

 a special trip for this office to the West, collected additional 

 material. The writer is greatly indebted to the following per- 

 sons for collections of flies made in kitchens and dining rooms 

 in different parts of the country, which collections are used as 

 important checks in this paper in determining which species are 

 most likely to carry bacteria from fasces to food : Professor W. B. 

 Alwood, Agricultural Experiment Station, Blacksburg, Vir- 

 ginia ; Professor H. A. Gossard, Agricultural Experiment 

 Station, Lake City, Florida ; Professor A. L. Quaintance, Ex- 

 periment, Georgia; Professor H. A. Morgan, Agricultural Ex- 

 periment Station, Baton Rouge, Louisiana; Dr. C. B. Daven- 

 port, University of Chicago, Chicago, Illinois ; Professor H. 

 B. Ward, University of Nebraska, Lincoln, Nebraska; Dr. R. 

 H. Ward, Tro}^ New York ; Alvin Davidson, Easton, Pennsyl- 

 vania. The writer himself made similar collections at different 

 points in California and at New Orleans, Louisiana, so that 

 most sections of the country were represented. 



GENERAL RESULTS OF THE INVESTIGATION. 



In summing up the results of the work carried on by the 

 w^riter the number of species of insects found breeding in or 

 frequenting human excrement was very large. There were 

 many coprophagous beetles — 44 species in all — and many Hy- 

 menopterous parasites, all of the latter having probably lived 

 in the larval condition in the larvae of Diptera or Coleoptera 



