SYNOPSIS OF THE SPECIES OF SAWFLIES BELONGING TO 

 THE GENUS DIMORPHOPTERYX. 



By S. A. Rohwer, 



Of the Bureau of Entomology , United States Department of Agriculture. 



The North American species belonging to the genus Strongylogaster 

 and to the section pinguis in Norton's classification were made into a 

 genus by Ashmead in his synopsis of the genera of sawflies. For a 

 number of years all the species belonging to this genus had been 

 assembled under one name, and biological notes on some of them 

 published under that name. In 1910 melanognathus was described 

 from one specimen from New Brunswick, Canada, and in 1911 

 Rohwer * tabulated the species and characterized certain forms as 

 varieties. Recent rearings and more careful study of the adult 

 brought three new species to light and also emphasized the specific 

 identity of the forms treated as varieties in the last-mentioned paper. 



This paper is a contribution from the Branch of Forest Insects, 



Bureau of Entomology. 



Key to the species. 



Scutellum strongly convex; transverse radius wanting; mesoprescutum rufous; 



basal plates pale abnormis Rohwer, p. 446. 



Scutellum not strongly convex; transverse radius present; mesoprescutum black; 



basal plates black or brown 1. 



1. Four apical abdominal segments black; (mandibles, antennae, clypeusand labrum 



black) melanognathus Rohwer, p. 446. 



Abdomen beyond basal plate pale except sometimes sheath is black 2. 



2. Females (scutellum yellow) 3. 



Males (scutellum usually black, though in one case, yellow) 7. 



3. Apical margin of the clypeus depressed; (clypeus subsquarely emarginate; lobes 



rectangular; the anterior margin pale; four anterior femora pale). 



errans Rohwer, p. 446. 

 Apical margin of the clypeus not depressed 4. 



4. Anterior margin of the clypeus arcuately or subangulately emarginate; lobes tri- 



angular 5. 



Anterior margin of the clypeus subsquarely emarginate; lobes rectangular 6. 



5. Antennae black; ocellar basin just below the ocellus shining, evenly concave, 



fanshaped virginica Rohwer, p. 446. 



Antennae pale; ocellar basin just below the ocellus with a furrow in the center. 



pinguis (Norton), p. 447. 



i Proc. U. S. Nat. Mus., vol. 41, p. 403, etc. 



Proceedings U. S. National Museum, Vol. 48— No. 2081. 



445 



