ICHNEUMONID.'E. 303 



Hah. — "West "Virginia, (Jas. Ridings). One 9 specimen. A beautiful species, 

 allied to /. detrUus- 



I. instabilis. — 9- Black or ferruginous, rather robust: head slightly narrow- 

 ed beneath, the anterior orbits more or less red or yellowish, sometimes the 

 head is entirely red or the face and clypeus are varied with brown and yellow- 

 ish or reddish ; antennae moderately long, not robust, generally fulvous at base, 

 yellow in middle and black at tips, sometimes only fulvous witli tips black, or 

 black at base, then fulvous, yellow and black ; third joint elongate, longer than 

 the fourth which is subequal with the fifth; thorax often entirely ferruginous or 

 more or less varied with ferruginous, sometimes black immaculate, except the 

 seutellum, which is always yellow and polished ; tegulse ferruginous, often with 

 a reddish spot in front and another beneath ; post-scutellum sometimes reddish ; 

 metathorax rugulose, the central area large and subquadrate; wings subhya- 

 line, more or less stained with yellow, nervures brown, stigma pale honey-yel- 

 low; legs honey-yellow or ferruginous; the coxae, tips of posterior femora, of 

 their tibise and most of their tarsi black, sometimes the most part of the jjoste- 

 rior legs is black; abdomen oblong-ovate, subconvex, slender at base, generally 

 entirely ferruginous, sometimes the fourth and fifth segments above are black 

 or fuscous, sometimes the second and third segments only are ferruginous, and 

 sometimes the incisures of the segments are more or less blackish ; beneath fer- 

 ruginous or yellowish-ferruginous, dusky or black at tip. Length b\ — 6 lines. 



%. This sex is exceedingly variable in color, some examples being almost 

 entirely yellowish-ferruginous, and others almost entirely black. Head black, 

 with the anterior orbits and all beneath the antennae yellow ; antennaj long, 

 slender, black above and brownish or fulvous beneath, the basal joint yellow 

 beneath; thorax generally black, sometimes more or less varied with ferrugi- 

 nous, and in one specimen the mesothorax has four abbreviated pale vittse; 

 sometimes the thorax is black, immaculate, except the seutellum which is al- 

 ways yellow; generally, there is a spot or a sutural line before the wings and a 

 spot or line beneath ; the post-scutellum is often reddish; legs honey-yellow; 

 the four anterior coxae often more or less yellow or honey-yellow, sometimes 

 black spotted with yellowish beneath ; the posterior coxae are generally black, 

 sometimes more or less ferruginous, their trochanters generally half black and 

 half honey-yellow, sometimes their femora are .entirely black or half black, ge- 

 nerally only tipped with black, rarely entirely honey-yellow, their tibiae tipped 

 with black; the general color of the legs varies from lemon-yellow to ferrugi- 

 nous; abdomen depressed, opaque, sometimes entirely yellowish-ferruginous, 

 but generally black, with the second and third, and sometimes part of the fourth 

 segments ferruginous or yellowish-ferruginous; the first segment is either en- 

 tirely ferruginous or black tipped with ferruginous, or with two apical j'eilow 

 sjiots; the second and third segments are entirely ferruginous, or yellow stained 

 with ferruginous; the fourth is either entirely black, or black spotted with fer- 

 ruginous, or entirely ferruginous, the remaining segments are generally black 

 or brown, often more or less varied with ferruginous; several specimens have 

 the second and third segments bright yellow and the rest black. Length 5 — 7 

 lines. 



Hab. — Me., Conn., X. Y., N. J., "W. Va. Twenty-seven 9) forty-four ^ speci- 

 mens. 



