It 



PROCEEDINGS OF THE 



ENTOMOLOGICAL SOCIETY OF WASHINGTON 



VOL. 24 APRIL 1922 No. 4 



ON THE TAXONOMIC VALUE OF LARVAL CHARACTERS IN 

 TACHINID PARASITES (DIPT.). 



BY \V. R. THOMPSON, Bureau of Entomology. 



The present paper, which deals with one of the parasites of 

 the European Corn Borer, is offered as a proof and an example 

 of the fact that in the family Tachinidae, it is at times almost 

 or quite impossible to define genera or species with the pre- 

 cision necessary in practical entomological work, with refer- 

 ence to the morphology of the adult flies alone. It sometimes 

 happens that species belonging to this group, though easily 

 separated by constant and well marked characters in the larval 

 stage are in the adult stage so similar that it is only possible 

 to separate them, by characters, whose value in the group as 

 a whole is so open to question, that to admit their validity in 

 general, would be to plunge the taxonomy of the family into 

 inextricable disorder Such is precisely the state of affairs in 

 the case of the parasites considered in this paper. 



In 1919, Madame A. Vuillet of the French Entomological 

 Service reared from specimens of Pyrausta nubilalis collected 

 in South-Western France, a Tachinid determined by Dr. J. 

 Villeneuve as the dark variety of Paraphorocera senilis Rond. 

 In the following year I reared further specimens of the same 

 form which were determined by the same authority. 



On comparing the primary larvae of the species reared from 

 the Corn-Borer with larvae extracted from a female labelled 

 Paraphorocera senilis in the collection of the Entomological 

 Museum of the University of Cambridge, I found that certain 

 well marked and constant differences in the conformation of 

 the bucco-pharyngeal armature existed between these larvae. 



A little later I sent to Dr. Villeneuve for determination a 

 lot of Tachinids among which were several specimens collected 

 in the garden of Haslar Hospital, near Portsmouth, England. 

 These were labelled by him as Paraphorocera senilis; but on 

 examining the larvae, of which I possess a large series, taken 

 from a number of different females collected on the same spot, 

 I found that they differed from those of both the other forms 

 mentioned above. 



On June 9, 1920, I collected in the garden of the laboratory of 



