280 u. s. national museum bulletin 216 



3. Tribe Ephialtini 



Figures 284; 298; 299,a 



Front wing 2.5 to 25 mm. long; clypeus usually a little swollen 

 basally, flattened or concave apically, its apex truncate or with a 

 median emargination ; mesoscutum without transverse wrinkling, its 

 notauli strong to obsolete; prepectal carina complete; mesopleural 

 suture without an angulation near the middle or sometimes with a weak 

 angulation ; propodeal carinae varying from complete (in some Xantho- 

 pimpla) to absent, often represented only by short, basal, median 

 longitudinal carinae (and the pleural carina); propodeal spiracle 

 elongate; last segment of tarsus sometimes enlarged; tarsal claws 

 large, in male simple, in female sometimes with a basal tooth, the 

 claws in three extra-limital genera with an enlarged hair with a flat- 

 tened tip; areolet present except in some Xanthopimpla; nervellus 

 broken always above the middle; first tergite free from its sternite, 

 its lateral carina usually strong; subgenital plate of male elongate, 

 with an acute or rounded apical point, rarely truncate or medially 

 emarginate; ovipositor stout, very short to moderately long, usually 

 weakly decurved, its apex a little depressed; in one genus hooked 

 downward at apex. 



Members of this tribe in most parts of the world are among the 

 commonest of all ichneumonids. These species are internal parasites 

 of pupae, usually of exposed or semiexposed pupae of Lepidoptera. 

 Species of Itoplectis are sometimes secondary parasites. The host 

 range of an individual species is usually very wide and, since hosts 

 of various sizes are attacked, the size of the parasite species varies 

 enormously. Males average smaller than females, which is the result 

 of the fact that an ovipositing female will usually lay a male (un- 

 fertilized) egg in a relatively small host and a female (fertilized) 

 egg in a larger host. It appears that a relatively large host will stimu- 

 late the ovipositing parasite to open its spermatheca when the egg 

 is laid so that it becomes fertilized, while a small host does not stimu- 

 late the parasite thus and receives an unfertilized egg which, as in 

 most Hymenoptera, produces a male offspring. Oviposition is into 

 pupae or prepupae. Emergence is always from the pupa. There is 

 one parasite per pupa. Overwintering is in the host pupa, or rarely 

 as an adult. 



There are seven genera in the tribe. Xanthopimpla, Echthromorpha, 

 Lissopimpla, and Strongylopsis are exotic so are not treated here. A 

 key to all but Strongylopsis may be found in Townes (1940, Ann. Ent. 

 Soc. America., vol. 38, p. 288). The three genera occurring in the 

 Nearctic region are keyed below. 



