U. S. D. A., B. E. Tech. Ser. 19, Pt. IV. Issued April 22, 1912. 



TECHNICAL RESULTS FROM THE GIPSY MOTH PARASITE LABORATORY. 



IV. The Chalcidoid Genus Perilampus and its Relations to the Prob- 

 lem of Parasite Introduction/ 



By Harry S. Smith, Expert. 

 INTRODUCTORY. 



Practical utilization of parasites in the control of noxious insects 

 is becoming a more and more important means of warfare in economic 

 entomology. For that reason accurate and detailed knowledge of 

 the life liistory of the various parasitic groups is indispensable to an 

 intelligent handling of the intricate problems wliich continually pre- 

 sent themselves m work of this kind. It does not suffice merely to 

 know that an insect is a primary parasite or a hyperparasite. Famili- 

 arity with the intimate details in its life and habits is of the utmost 

 importance in order that it may be brought to its maximum of effi- 

 ciency with the least possible delay; or, should it prove to be a 

 hyperparasite, that an injurious insect may not thus be released 

 unwittingly and irreparable damage be done. The great desirability 

 of bringing this phase of economic entomology to a position of promi- 

 nence has been the prime motive for a solution of some of the most 

 perplexing problems which have confronted the student of insect para- 

 sitism ; for example, the work of Marchal and Silvestri on the develop- 

 ment of the hymenopterous, and of Townsend and Nielsen on the, 

 dipterous parasites. These men are economic workers and their dis- 

 coveiies of the extraordinary phenomenon of polyembiyony or germi- 

 nogony in the parasitic Hymenoptera and of the unusual habits of 

 oviposition and larviposition in the tachinid parasites were made in 

 connection with a study of the practical utility of these insects in the 

 control of injurious species. Such investigations are interesting not 

 only from the purely scientific standpoint, but are more than justifi- 

 able from that of applied entomology. 



The few forms studied by these entomologists are among the most 

 common species, which goes to show how limited the present knowl- 

 edge of the biology of insect parasites really is. A fascinating field 

 of study is open to those in a position to undertake research of this 



> The writer is indebted to Mr. W. F. Fiske for valuable suggestions and criticisms throughout the 

 course of his work on Perilampus. 



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