132 tr. S. NATIONAL MUSEUM BULLETIN 216 parts 



Front wing 3.3 to 10 mm. long; body moderately slender; frons 

 unarmed; clypeus rather small and strongly convex, often pryamidal 

 in profile, its apical margin convex, sometimes with a median angu- 

 lation; flagellum of male nearly always with a median white band; 

 mesoscutum rather strongly arched, usually mat and with fine 

 punctures but more or less polished and impunctate in some Indo- 

 Australian species; notaulus moderately sharp, reaching to a little 

 beyond center of mesoscutum; epomia rather weak; prepectal carina 

 reaching or almost reaching the sub tegular ridge; propodeum of 

 moderate proportions, the basal carina complete, the apical carina 

 complete, interrupted medially, or sometimes absent, sometimes 

 forming a weak sublateral crest; propodeal spiracle circular or sub- 

 circular; areolet pentagonal, its sides strongly convergent; ramellus 

 very short or absent; nervulus opposite basal vein; mediella strongly 

 arched ; axillus close to anal margin ; first abdominal segment slender, 

 moderately widened apically, its spiracle far behind the middle, 

 with a lateral subbasal triangular point (weak in males, stronger in 

 females) ; dorsal and dorsolateral longitudinal carinae of first tergite 

 rather weak, the dorsal pair, if present, usually extending to a little 

 behind spiracle, the dorsolateral carina usually complete but weak; 

 ventrolateral longitudinal carina of first tergite complete; second 

 tergite mat, with moderately small punctures that vary in density 

 from sparse to close; tergite 7 without a median white spot but 

 sometimes its apical margin white or yellow; ovipositor sheath about 

 0.30 as long as front wing; ovipositor rather slender, compressed, its 

 tip sagittate. 



Ischnus is almost world-wide in distribution, but the species are 

 numerous only in the mountainous parts of the Oriental region. In 

 the Nearctic region we have eleven species. Several of these are 

 widely distributed and quite variable in both color and structure. 



The species are parasitic on lepidopterous pupae. A number of 

 reared specimens of several species are at hand, with their cocoons. 

 The cocoons are elongate elHptic, rather thin, with loose silk on the 

 outside, and white to light brown in color. They are spun partly or 

 entirely inside the host pupal shell, or alongside it. 



Key to the Nearctic gpecies of Ischnus 



1. Apical transverse carina of propodeum distinct and sharp medially . . 2 

 Apical transverse carina of propodeum lacking or very indistinct medially, 



sometimes the entire carina lacking 5 



2. Basal 0.2 ± of hind basitarsus fuscous or ferruginous; punctures on second 



tergite of female separated by about 3.0 their diameter; hind tibia not white 

 basally 4. sparsus, new species 



