2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



whig without any speculum, costal cell with many hairs along margin. 

 Postmarginal vein longer than marginal vein. Stigmal vein short, 

 about one-third length of marginal vein. 



In the Nearctic region there are five known species. I describe two 

 new species in the present paper. 



The species of Epistenia are primary parasites of solitary nesting 

 aculeate Hymenoptera. Rau (1922) reared E. osmiae Ashmead (now 

 considered a synonym of E. coeruleata) from an elder twig that had 

 been tunneled by Ceratina species or Ectemnius (Hypocrabro) species. 

 Parker and Bohart (1966) reared E. coeruleata from Isodontia elegans 

 (Smith) and Trypargilum tridentatum tridentatum (Packard) nesting 

 in borings in Sambucus stems. Epistenia regalis Cockerell (1934) (a 

 probable synonym of E. coeruleata) was described originally from a 

 specimen reared from the nest of an odynerid wasp. The original 

 hosts of E. osmiae and E. odyneri Ashmead are obvious from their 

 names; the first was described from a specimen reared from an Osmia 

 species in a catalpa twig, and the second emerged from burrowings 

 of Odynerus (now Leptochilus) rufobasilaris Ashmead in twigs of 

 Nama. There are in the USNM collection specimens of E. coeruleata 

 that were reared by J. C. Bridwell from Trypargilum collinum 

 rubrocinctum (Packard) and by K. V. Krombein from Leptochilus 

 republicanus zendaloides (Robertson). The latter rearing was from a 

 sumac stem boring. 2 



Key to Nearctic Species of Epistenia 



1 . Hind tibiae with long bristles, 2-3 times breadth of tibia . . odyneri Ashmead 

 Hind tibiae with short spines, shorter than breadth of tibia 2 



2. Malar space as long as half breadth of an eye. Distance between upper edges 



of antennal scrobes twice diameter of an ocellus . . . burksi, new species 

 Malar space as long as or nearly as long as breadth of an eye. Distance be- 

 tween upper edge of antennal scrobe and front edge of median ocellus only 

 equal to or less than diameter of ocellus 3 



3. Wings distinctly smoky polita (Say) 



Wings hyaline, without darker clouds 4 



4. Last tergite of gaster short, about one and one-half times as long as its basal 



breadth media, new species 



Last tergite of gaster long, more than twice as long as its basal breadth ... 5 



5. Tegulae black regalis Cockerell 



Tegulae yellowish brown coeruleata Westwood 



Epistenia odyneri Ashmead 



Epistenia odyneri Ashmead. — Davidson, 1896, p. 336. 



This species differs from the other species from the Nearctic region 

 in having long bristles on the hind tibia (fig. 5d). Originally described 

 from California. The author has seen a male specimen from Arizona 

 (Grand Canyon, Bright Angel Trail, May 15, 1952, E. B. Haydon, Jr.). 



2 Paragraph added by B. D. Burks. 



