204. PROCEEDINGS OF THE NATIONAL MUSEUM Vou. 1138 
Hosr piants: With certain exceptions, the known host plants of 
species in this subgenus are species of Cuscuta (dodder). Some species 
which probably do not breed in Cuscuta are S. lutulentus Dietz, S. 
profusus Casey, and S. halophilus Blatchley. 
DisTRiIBuTIoN: Species placed in this subgenus are known to occur 
in North America, South America (three described species), Europe, 
Asia, and Africa. 
Key to the Species Groups of Subgenus Smicronyx 
1. Size very large, almost always over 3.5 mm. in length, sides of prothorax 
subparallel for over half their length (fig. 20); rostrum of female smooth, 
elongate, and polished before antennal insertions (fig. 22). 
profusus group (p. 257) 
Size smaller, almost always less than 3.0 mm. in length, sides of the prothorax 
usually rounded, not subparallel, rostrum of female not smooth, elongate, 
and polished before antennal insertions (figs. 3, 14) .......... 2 
2. Setiform scales of prothorax and elytra large and conspicuous. 
quadrifer group (p. 248) 
Setiform scales of prothorax and elytra not contrasting conspicuously with 
rest Of Scales: ( vacates tsb oA © Bi ecg) Ole seh Gt eg cco 3 
3. Rostrum distinctly unicarinate or bicarinate medially in both sexes .... 4 
Rostrum not medially carinate (striate at the most) in either sex ...... 5 
4. Prothorax marked with a broad and complete median stripe of white scales; 
male genitalia as in figure 71; rostrum of female tapered and shining before 
antennal insertionsi(fis13)i a 4 © eee Sie cne spretus group (p. 259) 
Prothorax never marked with a median white stripe; male genitalia not as 
in figure 71; rostrum of female not tapered or shining before antennal 
AMSETCIOMS).~ Mes se) Gens By Hue sainsas oly aoe seine cach teams cinereus group (p. 204) 
5. Prothorax deeply punctate and/or sculptured, the scales of elytra in trans- 
verse bands, fasciae or scattered patches (except in S. vestitus LeConte and 
S.halopnilus Blatchley): 9s... S44. eee ee sculpticollis group (p. 216) 
Prothorax not deeply punctate or sculptured; scales of elytra fairly evenly 
distributed “ceticsecsc is as css. eu oi Soko Mon Geel felmopne tye instabilis group (p. 237) 
SMICRONYX CINEREUS GROUP 
Description: Body oblong-ovate, moderately stout (fig. 11). 
Rostrum stout, moderately curved (fig. 12), carinate dorsally. 
Prothorax moderately rounded on sides, narrowed and constricted 
toward apex; disk deeply, evenly, and usually closely punctate (fig. 
11). Elytra slightly wider behind middle than at base, setiform 
scales small, declivities distinct (fig. 11). Median lobe of male 
genitalia fairly short, lightly sclerotized dorsally, broader at apex 
than at base (except in S. cuscutiflorae Pierce), spines of internal sac 
never large and conspicuous (figs. 50-52). 
Discussion: The species in this group seem to be the best example 
of the basic characteristics of subgenus Smicronyz. The other groups 
show some modification of these basic characteristics (or at least 
differ from the basic plan in some way) and may be distinguished from 
