SMICRONYX WEEVILS—ANDERSON 197 
the work of Scudder (1893) has shown that a number of other pres- 
ently existing genera of Curculionidae (e.g., Anthonomus, Tychius, 
Apion) are apparently represented by fossils in the Miocene shales 
at Florissant, Colorado. 
1. INTERMEDIATES: This step involved the development of a few 
species (some of which still exist) which shared the general charac- 
teristics of subgenus Smicronyx but have a much longer, more tapered, 
polished rostrum in the female than in the male. S. profusus Casey 
is the best example of this (see figs. 21,22). Of these species none is 
known to breed in Cuscuta. 
Discussion: The species characterized above appear to be inter- 
mediate in form between the rest of subgenus Smicronyx and the 
species of subgenera Pachyphanes, Pseudosmicronyx, and Desmoris. 
The various species of Cuscuta, which may have served as hosts 
to the early species of Smicronyx, probably parasitized a large variety 
of plants, as is true of many present species of Cuscuta. ‘The adult 
weevils, although primarily associated with the Cuscuta, probably 
visited the flowers of the plants which supported the Cuscuta and the 
flowers of other plants nearby, and sometimes fed on the tender parts 
of those flowers. Possible examples of this are the records of S. 
tychoides LeConte and S. sculpticollis Casey taken on Ambrosia 
although both species are known to breed in Cuscuta. The reverse 
situation, i.e., species which are known to breed in some plant other 
than dodder but are occasionally found on dodder, is not known to 
occur. Feeding and egg laying are fairly closely associated activities 
in most female weevils (the female chews a cavity for each egg), 
and it seems possible that females of some of the early Smicronyx 
species occasionally oviposited by ‘‘mistake”’ in the flowers of some of 
the plants they visited. If the larvae hatching from the eggs laid 
in those flowers found the plants acceptable as food, they may well 
have completed their growth, pupated, and attained the adult stage. 
A situation somewhat similar to the hypothetical one just described 
has been observed in nature. In a few recorded instances, the lar- 
vae of Smicronyzx sculpticollis Casey, a species recorded many times 
as breeding in Cuscuta, have been found burrowing in the stems of 
certain composites on which Cuscuta was growing. (Further details 
are given below, in the discussion of the biology of S. sculpticollis.) 
Because of these ‘‘mistakes”’ coupled with preimaginal condition- 
ing, certain species could have developed alternate hosts, which they 
used occasionally instead of Cuscuta. Under the influence of selective 
pressure, the source of which is uncertain to the writer, some Smicro- 
nyx species may have come to live entirely on host plants which 
had formerly been only alternates to Cuscuta. These forms may 
have been ancestral to the species suggested to have developed in 
