16 MISC. PUBLICATION 241, U. S. DEPT. OF AGRICULTURE 
Key to the Nearctic Species of Microctonus—Continued 
5. Radial cell about half as long as stigma; second abscissa of radius strongly 
arched!) OU 38 ieel Ce Ghee he a eee (4) eleodis (Viereck). 
Radial cell nearly as long as stigma; second abscissa of radius weakly 
CUBVEG 22,67. poe ed hs ee (3) nigritus (Provancher). 
6. First abdominal tergite without lateral carinae from spiracles toward base, 
three times as long as broad at apex, the petiole very slender and 
ee face smooth and shining; temples and cheeks narrower than 
CYOS. 2 le Leys) i cs ta age A ep Re tyre ea ae (6) epztricis (Viereck). 
First spaowianl tergite with lateral carinae from spiracles toward base, 
not three times as long as broad as apex, the petiole usually more or 
less sculptured; face finely punctate or granular; temples oe cheeks, 
atvleast in malevas broad. as eyes =a a ane unin eee Pie 7 
7. Middle iobe of mesoscutum irregularly weakly punctate or wailed: hairy; 
no median carina posteriorly on mesoscutum; malar space as long as 
basal width of mandible; first abscissa of radius about half as long as 
width of stigma; lower abscissa of basella not so long as nervellus. 
Known only in female sex______-______-_- (7) vittatae, new species. 
Middle lobe of mesoscutum smooth, and bare except for a few scattering 
hairs in front; a median longitudinal carina posteriorly on meso- 
scutum; malar space shorter than basal width of mandible; first 
abscissa of radius less: than half width of stigma; lower abscissa of 
basella as long as nervellus____________-- (8) pusillae, new species. 
(1) MICROCTONUS CARABIVORUS, new species 
(Fig. 1, D) 
Superficially rather similar to mellinus, but readily distinguished by 
the bare lateral lobes of the mesoscutum, the narrow stigma, the 
unusually long lower abscissa of basella, the more or less areolated 
propodeum, and by having fewer segments in the antennae. 
Female.—Length 2.5 mm. Head transverse; eyes large, prominent, nearly 
twice as broad as temples; occipital carina only very narrowly interrupted 
medially; face not broader than long, nearly smooth; malar space much shorter 
than basal width of mandible; frons smooth except for slight roughening just 
above antennae; vertex convex; postocellar line about twice diameter of an ocellus 
and a little shorter than ocellucular line; antennae about as long as body, 24-seg- 
mented; flagellum of uniform thickness throughout, its basal segment slightly 
longer than second; scape one and one-half times as long as pedicel. 
Thorax much narrower than head, very sparsely pubescent; notauli foveolate, 
lateral mesonotal lobes polished and bare, the middle lobe with scattered, very 
shallow punctures and sparse pubescence; impression at base of scutellum broad 
and deep, divided by a prominent median longitudinal carina; scutellum very 
small; propodeum irregularly coarsely reticulate, with a suggestion of areolation, 
rather abuptly declivous behind; side of pronotum smooth except for a few rugae 
in the longitudinal impression; mesopleurum mostly polished, with a coarsely 
foveolate longitudinal groove below; stigma narrow; radial cell about two-thirds 
as long as stigma; first abscissa of radius perpendicular to anterior margin of 
wing, more than half as long as width of stigma, and longer than nervulus; second 
abscissa only slightly curved; lower abscissa of basella much longer than upper 
abscissa or nervellus; nervellus not distinctly longer than longest marginal cilia 
of posterior wing; legs very slender; hind coxae polished. 
Abdomen a little longer than thorax and nearly as wide in its widest part; first 
tergite long and slender, longer than second and third combined, three times as 
long as broad at apex, more or less striate, smooth at apex, the spiracles a little 
beyond middle; ovipositor sheaths very slender, longer than hind femur but not 
so long as hind tibia. 
Testaceous; antennal flagellum brownish, a little paler below toward base; 
ocellar area, lateral lobes of mesoscutum, and more or less of dorsal face of pro- 
podeum somewhat piceous; middle lobe of mesoscutum and scutellum ferrugi- 
nous; legs entirely yellow; wings hyaline, stigma pale brown, its margins slightly 
darker, veins yellowish hyaline; lateral edges of postpetiole of first tergite blackish. 
Male.—Essentially as in the female except that the antennae are considerably 
longer than the body, 26-segmented in the allotype, with first flagellar segment 
not longer than second; and the face, temples, and cheeks relatively broader. 
