REVISION OF THE CHALCID FLIES OF THE TRIBE DE- 

 CATOMINI (EURYTOMIDAE) IN AMERICA NORTH OF 

 MEXICO 



By W. V. Balduf 



Universiti/ of Illinois, Urhana, Illinois 



INTRODUCTION 



The family Eurytomidae is one of the least studied groups of the 

 large superfamily Chalcidoidea. On account of the outstanding eco- 

 nomic importance of its species as pests on grasses and small grains, 

 the genus HarmoUtcD Motsch has received more attention than any 

 other of this family. Sundry habits are represented in the very diffi- 

 cult genus EwytoTna Illiger, the outstanding one probably being para- 

 sitism on other insects. Comparatively little is known about the lat- 

 ter group, and still less information has been produced regarding the 

 biology of the Decatomini and most of the smaller genera falling 

 within this tribe. The fact that the Decatomini are mostly galli- 

 colous explains the absence of a larger body of facts about their 

 habits, and only a few workers, chiefly of the present day, seem to 

 have been at all interested in preserving specimens of this tribe reared 

 from galls incident to their study of the Cynipidae. As a result, most 

 of the species of the group are represented by relatively small series 

 of specimens, and many species probably still remain undiscovered. 

 The present revision treats 30 species and 5 varieties, of which 14 

 species and 3 varieties are new. The species previously recorded in 

 the literature were described by Fitch, Walsh, Ashmead, Girault, and 

 Fullaway. The present intensive work of Dr. A. C. Kinsey and 

 L. H. Weld on the Cynipidae has produced most of the new material 

 described herein. In addition to the material received from Messrs. 

 Kinsey and Weld, and specimens reared myself, I have studied the 

 Decatomini in the collections of the United States National Museum, 

 the Canadian Department of Agriculture, a series from Stanford 

 University, California, a small lot belonging to the Illinois State 

 Natural History Survey, and a few specimens from several 

 other State and personal collections.^ It is to be hoped that the rear- 



^ No doubt additional specimens are housed in various museums of North America, and 

 I shall welcome the opportunity to studj' any such material that anyone will send me at 

 the University of Illinois, Urbana, III. 



No. 2894.— Proceedings U. S. National Museum. Vol. 79. Art. 28 



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