352 U. S. NATIONAL MUSEUM BULLETIN 216 



septemtrionalis are related to Neo tropic species, while atalantae and 

 hilaris are representatives of a large group of species centered in the 

 Oriental region. 



The species of Theronia are medium-sized ichneumonids with the 

 ovipositor sheath about half as long as the abdomen, or longer or 

 shorter in a few of the exotic species. They inhabit mostly dense 

 forests. Some of tbem fly close to the ground, but others commonly 

 fly up to waist or shoulder height if there is undergrowth at those 

 levels. Nearly all are pale-colored, usually pale yellow to ferrugi- 

 nous, and frequently banded with blackish. In flight they make a 

 conspicuous pale streak through the dark forest. When caught they 

 sink their large sharp claws into the net or their captor and are often 

 hard to disengage without breaking the claws. This habit and the 

 presence of a large fluid-filled pocket in each claw at the usual place 

 of breaking has led to speculation as to whether the claws may 

 function as a sort of poison fang (Townes, 1940, Ann. Ent. Soc. 

 America, vol. 33, pp. 285-287). Definite evidence on this question 

 is still lacking. Probably most species are primary or secondary par- 

 asites of a variety of Lepidoptera. A Philippine species, however, 

 has been reared from a nest of Stenogaster (Vespidae), this rearing 

 having been reported as an unidentified parasite by Williams (1919, 

 Bull. Experiment Sta. Hawaiian Sugar Planters Assoc, Ent. Ser., 

 vol. 14, p. 173). 



The Nearctic species of Theronia were treated by Townes in 1940 

 (Ann. Ent. Soc. America, vol. 33, pp. 289-298). The treatment 

 below is similar to that. 



Key to the Nearctic species of Theronia 



1. Front wing with a definite dark spot near the apex; propodeum with a trans- 



verse carina across its middle and no carinae basad of the transverse 



carinae (fig. 314,c) 3. septemtrionalis (Krieger) 



Front wing without a definite dark spot near the apex; propodeum with a 

 less regular transverse carina across its middle and with definite longitudinal 

 carinae basad of the transverse carina (figs. 314,a,b,d) 2 



2. Prepectal carina incomplete above, its upper end far from front edge of meso- 



pleurum; abdomen banded with brown and yellow . 4. bicincta (Cresson) 

 Prepectal carina complete above, turned forward toward and almost reach- 

 ing front edge of mesopleurum; abdomen in Nearctic forms uniformly 

 fulvous, or sometimes the tergites brown basally 3 



3. Hind femur sharp beneath for part of its length, and in all except unusually 



small specimens with a weak irregularly serrate carina (fig. 299, b) ; head 



yellow and light fulvous 1. atalantae (Poda) 



Hind femur rounded beneath, never with a carina; head black, the face 

 often more or less ferruginous 2. hilaris (Say) 



