PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 



Vol. 99 Washington : 1949 No. 3243 



THE NEARCTIC SPECIES OF THE FAMILY 

 STEPHANIDAE (HYMENOPTERA) 



By Henry Townes 



The Stephanidae are a family of relatively large, elongate parasitic 

 Hymenoptera usually regarded as rare, but sometimes common in the 

 Tropics. They have a spherical head, long neck, stalked abdomen, 

 long hind coxa, swollen hind femur, and long ovipositor: characters 

 that together give an appearance unlike any other insects except 

 certain groups of Braconidae. In these features (except the oviposi- 

 tor length) the primitive genus Schlettererius is conservative, and 

 the more specialized genera progressively more extreme. 



The family may be at once distinguished by habitus (pi. 25, figs. 1, 

 2) and the crown of five blunt to acute teeth surrounding the median 

 ocellus of all species. The multisegmented antenna, the wing vena- 

 tion, and other structural features suggest close relation to the Brac- 

 onidae. The crown of teeth on the head, shape of the mandible, 

 venation, and some other features are reminiscent of the Orussidae. 



Stephanids are often collected on dead tree trunks. Because of 

 this and their habitus, the species are generally presumed to be para- 

 sites of wood-boring Coleoptera. Other possible hosts are aculeate 

 Hymenoptera nesting in wood. The only known rearing record is of 

 a short series of Diastephmms leueostictus in the United States Na- 

 tional Museum, from Agrihis kalshoveni in Java. The adults are 

 sluggish and awkward in walking and slow in flight. 



Two genera containing six species are known from America north 

 of Mexico. The types of the described species have been studied, 

 except for these of the names Stephanus Hcoloi" Westwood and S. 

 sickmanni Schletterer. Most of the specimens studied are in the 



818708 — 49 361 



