192 PROCEEDINGS OF THE NATIONAL MUSEUM Vou. 113 
MsAsurEMENTS: The statistical comparisons of S. cinereus Mot- 
schulsky and S. obscurus, new species, S. lutulentus Dietz and S. 
albonotatus, new species, and S. flavicans LeConte and S. immaculatus, 
new species, indicate that measurements often differ significantly 
between apparently related species. Further quantitative comparisons 
of species and groups of species may reveal much more about the 
reliability of such characters as body length and the relative size of 
various body parts. 
BIOLOGY 
Nortn AMERICAN spEcIES: The biologies of only a few North 
American species of Smicronyr have been studied in detail. In gen- 
eral, the weevils are known to breed in the seeds and/or stems of 
various herbaceous plants, particularly species of Cuscuta (Convol- 
vulaceae) in the subgenus Smicronyx, and various genera of the 
tubuliflorous Compositae in the other three subgenera. However, 
several other plant families are represented among the possible or 
probable hosts (see table 1, pp. 193, 194). 
From the studies of Pierce (1907) on Smicronyx (S.) tychoides 
LeConte and S. (Desmoris) scapalis LeConte, of Weiss and West 
(1921) on S. (S.) sculpticollis Casey, and of Rempel and Shevkenek 
(1941) on S. (Pseudosmicronyz) utilis Buchanan, a few generalizations 
about the life history pattern of the genus are possible. The adults 
apparently appear on the host plants early in the summer, after which 
they feed on tender flower and leaf parts while engaging in copulation 
and oviposition. The larvae feed on tbe seeds or internal tissues of 
the host plant until fully grown, after which they usually emerge from 
the plant, burrow into the soil, where they spend the winter, and 
pupate sometime late in the spring. Some species (i.e., S. sculpticollis 
Casey and S. cuscutiflorae Pierce) may pupate in the plants. The 
number of larval instars is unknown, with the exception of S. utilis, 
which has four. 
Some of the species which breed in Cuscuta (1.e., S.  tychoides 
LeConte and S. sculpticollis Casey) cause galls to form on the stems, 
while other species such as S. cuscutiflorae Pierce breed in the seed 
capsules of the Cuscuta. Those species which breed in plants other 
than Cuscuta (e.g., S. utilis and S. scapalis) generally breed in or among 
the seeds. 
The host-plant information gathered from the specimens examined, 
from the literature, and from field work has been condensed and set 
forth in table 1 below. The first number in each column indicates the 
number of species in the subgenera of Smicronyr that have been 
found in association with plants of the family or genus indicated on 
the left side of the table. The next figure, separated from the first by 
a colon, indicates the number of species actually reared from plants of 
