February, '19] headlee: SPRINKLING sewage filter fly 35 



pointment of his committees and thus actively assist in carrying out 

 the poHcies that he proposed. 



The Economic Entomologists will become more active and aggres- 

 sive, if they fulfill their destiny and keep abreast of the progress of the 

 modern world. They will broaden and strengthen their courses of 

 instruction, insist on fundamentals and foundations in all branches. 

 They will require longer and more adequate preparation for research 

 and thus establish standards beyond reproach. They will welcome 

 criticism, be generous in credit, seek cooperation; they will ally them- 

 selves with all forces that fight for the freedom of the earth from pest 

 and disease. They will have faith to attempt the impossible and 

 finally triumph, as do all forces that battle for truth and right. 



At the close of the address a vote of thanks was extended by the as- 

 sociation, after which the session adjourned. 



Afternoon Session, Thursday, December 26, 1918, 2.1^0 p. m. 



President E. D. Ball: We will now take up the first paper on 

 the program, by T. J. Headlee, New Brunswick, N. J. 



PRACTICAL APPLICATION OF THE METHODS RECENTLY 



DISCOVERED FOR THE CONTROL OF THE 



SPRINKLING SEWAGE FILTER FLY 



{Psychoda alternata) 



By Thomas J. Headlee, Ph. D., Entomologist of the New Jersey Agricultural Experi- 

 ment Stations and Stale Entomologist 



Introduction 

 Except where trade wastes are discharged in sufficient quantities 

 materially to affect the effluent, sewage purification is essentially a 

 process of transforming chemically unstable compounds into those 

 which are chemically stable, and a process of reducing the number of 

 pathogenic organisms to the lowest possible point, to the end that the 

 water which has been used as a carrier for the sewage matters may 

 be discharged into streams without polluting them in such a way as 

 to be a menace to human health. The transformation of the chem- 

 ically unstable sewage compounds to the chemically stable is appar- 

 ently a bio-chemical process. The society of animals and plants 

 effecting this change apparently reaches its highest development in 

 the sprinkling sewage filter. The broken stones of which the body of 

 this type of filter is composed are more or less completely coated with 

 a gelatinous and amorphous film in which live the millions of organisms 

 which effect this transformation. The organisms concerned are repre- 

 sentatives at least of Bacteria, Fungi, Protozoa, Nematoda, Rotatoria, 



