PROC. ENT. SOC. WASH., VOL. 23, NO. 9, DEC., 1921 203 



with Semiotellus nigripes Lindemann described in 1887. Sub- 

 sequently the species was placed by W. R. McConnell at the 

 suggestion of A. B. Gahan in the genus Pleurotropis. 



The great abundance of the Hessian fly in England in 1886 

 and 1887 enabled Dr. Riley, who was then abroad, to study its 

 parasites in some detail. The most abundant of these parasites 

 proved to be the species under discussion, and it was at that 

 time that the idea was conceived that the artificial introduction 

 of the parasite might prove of the greatest practical value to 

 the wheat growers of the United States. The idea was based 

 on the well-recognized fact that European insects often increase 

 in excess of their normal abundance when introduced into 

 foreign countries. With this idea in view, a quantity of para- 

 sitized Hessian fly puparia were sent by Mr. Frederick Enock of 

 London in 1891, and were received and released by Prof. F. M. 

 Webster at Lafayette, Indiana, by Prof. S. A. Forbes at Cham- 

 paign, Illinois, and by Prof. A. J. Cook at Agricultural College, 

 Michigan. Later a supply, sent by Prof. Forbes from Cham- 

 paign, Illinois, was released by Dr. James Fletcher, Dominion 

 Entomologist, Ottawa, Canada. 



The material sent to Prof. Forbes was placed in an enclosed 

 plat experiment and rearings therefrom were released by him. 

 There are published records of recoveries of this species and 

 hints of the ultimate success of the experiments conducted by 

 Prof. Forbes, but there do not appear to be any reports from 

 Prof. Webster, Prof. Cook, and Prof. Fletcher. Additional 

 material received from Mr. Enock in 1894 was released at 

 Cecilton, Md., and Fredericktown, Md. Mr. William H. 

 Ashmead, in May, 1895, collected one specimen at Cecilton, 

 Md , but we have no record of its successful introduction at 

 Frederick, Md., until April 19, 1917, when the junior author 

 reared a male from Hessian fly puparia secured at that locality. 

 The records of two other males and three females from that 

 locality were also secured between May 26, 1917, and March 26, 

 1921. All other specimens appear to have been liberated, as 

 Dr Riley quaintly says: "Under such conditions as to warrant 

 the expectation of continuous breeding." 



For many years the results were not marked, and, as indicated, 

 only two positive reports as to the establishment of the parasite, 

 those from Prof. Forbes, and Mr. Ashmead were received. The 

 lack of evidence from the other points of introduction seems due 

 almost entirely to lack of proper examinations by those having 

 trained eves for minute forms, and to lack of familiarity with 

 this and allied species. No further records of recoveries were 

 found until 1915, when rearings were made by Mr. W. R. Mc- 

 Connell and the junior author from material collected at 

 Hagerstown, Md., Andersonburg, Pa., Ford City, Pa., Green- 

 ville, Pa., Warfordsburg, Pa., and Montoursville, Pa. A brief 



