ICHNEUMON-FLIES — GELINAE I MESOSTENINI 477 



slender, in female its apex abrupt because of an apical sensory disc 

 or a truncate, short apical peg or flange; thorax usually long; 

 propodeum usually long, its basal transverse carina usually strong, its 

 apical transverse carina present or absent, when present usually 

 without sublateral crests and never forming sublateral teeth; propodeal 

 spiracle round to elongate; front tibia of female inflated, its base 

 narrow; fourth tarsal segments of female with a compact group of 

 apical bristles on underside that are not or only wealdy divided on the 

 midline, the segment not distinctly bilobed apically (see from under 

 side); areolet varying from unusually large to very small, pentagonal, 

 square, or rectangular, when small often open apically; fu"st tergite 

 more or less widened apically, the widening rather gradual ; spiracle of 

 first tergite at, a little in front of, or definitely behind the middle; 

 abdominal tergites 7 and 8 of female usually enlarged; female sub- 

 genital plate not unusually large and sclerotized; ovipositor moderately 

 short to long, always projecting conspicuously beyond apex of 

 abdomen, more or less compressed, the tip of lower valves with a dorsal 

 lobe that encloses or partly encloses the tip of upper valve (except in 

 Helcostizus and in some species of Echthrus); apical teeth on lower 

 valve of ovipositor tending to form close vertical ridges; upper valve 

 without apical teeth, but its dorsal edge often rippled. 



This is a moderate-sized group that is parasitic on wood borers. 

 Most of the species are tropical, but there are five genera in our area. 



\ 



Key to the Nearctic genera of Echthrina 



1. Spiracle of first abdominal tergite near its apical 0.43; first tergite with median 



dorsal carinae distinct, at least near the spiracle; ch'peus vdth a strong 



median point 1. Xylophrurus( p. 478) 



Spiracle of first abdominal tergite at or a little in front of its middle; first 

 tergite without median dorsal carinae except in Helcostizus annulicornis . 2 



2. Basal transverse carina of propodeum absent or obsolescent, the apical trans- 



verse carina strong; clypeus with a median apical tooth in the Nearctic 

 species; areolet large; second tergite not distinctly punctate. 



2. Echthrus (p. 486) 



Basal transverse carina of propodeum strong, the apical transverse carina 



often absent; clypeus without a median apical tooth 3 



3. Nervulus distad of basal vein by about 0.3 its length (fig. 326, a) ; basal trans- 



verse carina of propodeum angled strongly forward at the middle (fig. 326, a) ; 

 areolet small; nervellus broken near its lower 0.35 . . 5. Helcostizus (p. 513) 

 Nervulus basad of basal vein by about 0.3 its length; basal transverse carina 

 of propodeum rather evenly curved, not strongly angled forward at the 

 middle 4 



4. Areolet small (fig. 325,a) ; nervellus broken above the middle; sternaulus 



present, though usually weak 3. Agonocryptus (p. 502) 



Areolet large (fig. 325,b) ; nervellus broken below the middle; sternaulus 

 absent 4. Cryptohelcostizus (p. 504) 



