U. S. D. A., B. E. Tech. Sor. 19, Pt. V. lasiied May 29, 1912. 



TECHNICAL RESULTS FROM THE GIPSY MOTH PARASITE LARORATORY. 



V. Experimental Parasitism: 

 A Study of the Biology of Limnerium Validum (Cresson). 



By P. H. TiMBERLAKE, A. M., 



Agent and Expert, Gipi^!/ Moth Parafiite Lahoratonj. 

 INTRODUCTION. 



The biology of none of our American parasitic Hymenoptera is 

 too well knoAvn to demand an apology for the appearance of this 

 article, and it is the hope of the author that the results of the studies 

 here set forth will call to the attention of our professional and 

 amateur entomologists this exceedingly rich but almost untouched 

 field for investigation. A little of the ecology, especially of the 

 host relationship, of many of our parasites has been recorded, but 

 the various and interesting adaptations in the larval structure and 

 habits of our different species are almost unknown. 



In connection with the practical work at the Gipsy Moth Parasite 

 Laboratory of importing and liberating parasites of the gipsy and 

 brown-tail moths, considerable attention is paid to the habits and 

 biology not only of the imported parasites, but also of our native 

 parasites of caterpillars that resemble the gipsy moth or browni-tail 

 moth in habits or destructiveness. In this w^ay considerable knowl- 

 edge has accumulated wdiich, besides its intrinsic and theoretical 

 value, has been useful in perfecting the methods of handling the 

 imported species and in showing which of our American species, if 

 any, may be expected to become contributing factors in the control 

 of these pests. 



It was especially with this latter idea in mind that in the spring 

 of 1910 a series of experiments was undertaken to w^ork out the 

 biology of our native Limnerium validum (Cresson) (fig. 32) and 

 its behavior toward unusual hosts. The experiments grew^ out of a 

 successful attempt to foster oviposition on small brown-tail moth 

 caterpillars {Euproeth ehrysoiv'ha'a Linnaeus), which yielded such 

 unexpected complications that the work w^as continued on other hosts 

 as they became available in the course of the spring. 



LimnenuTrh validum proved to be an excellent subject for experi- 

 mentation for several reasons, but chiefl}' on account of its docility in 



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