Weevils - Entomological Society of Canada

Distribution. Alberta, south through the central and western
United States to Arizona and Texas, east to Missouri and Minnesota'
Alberta: Scandia.
Comments. This species is a member of the subgenus Fallapion.
Adults are distinguished from other members of the subgenus by the
fine striae on the polished area on the male front femora, by the
comparatively slender elytra, and by the relative length of the rostrum
compared to the length of the pronotum. In addition, the elytral humeri
are prominent and the legs are generally reddish. Adults have recently
been implicated in the transmission of a fungal disease, black stem of
sunflowers. Spores of fungus have been found on the antennae and
mesothoracic and metathoracic legs of both wild and laboratory adults.
Fungal hyphae were observed on the rostrum of adult weevils (Gaudet
and Schulz 1984). In North Dakota and Minnesota, Apion occidentale
overwinters as an adult and begins feeding on sunflowers (Helianthus
species) as soon as the plants emerge in the spring. Adults feed on the
leaves and stems from early spring to late July. Females deposit their
eggs under the epidermis ofthe stem; larvae tunnel in the pith area ofthe
stem, pupate, and emerge as adults in late July or early August. The
insects are mostly or wholly inactive for a period of about 2 weeks in late
July or early August. Adutts emerging in August feed on the leaves and
stems of the plant, but as the plant matures and the leaves become
senescent, the adults move under the involucral bracts of the sunflower
head, where they remain feeding until winter or until the plants are
harvested (Gaudet and Schulz 1981). The feeding ofadults and larvae
does not cause significant mechanical damage to cultivated sunflowers,
but the transmission of black stem of sunflowers may make this species
economically important. In addition to sunflowers, adults have also
been taken on Haplopappus species and Coreopsis species (Salisbury
1984). Kissinger (1968) designated the lectotype ofthis species.
Apion opacicol/e Smith
Figs. 112, 113, I42, I43
Apion. opacicolle Smith, 1884:51 (lectotype, "Rey Co."; USNM);
Kissinger 1968:13; Hatch l97L:327; O'Brien and Wibmer 1982:25'
Description. Length 7.6-2.5 mm. Body moderately slender,
black. Pubescence consisting of yellowish, very fine, very sparse scales'
Frons 7.0-L.2 times wider than tip of rostrum. Rostrum of male slightly
curved, I.2-L.}times longer than pronotum; sides, in dorsal view, nearly
parallel in apical third, slightly expanded at antennal insertion; surface
alutaceous, with fine, short scales to near tip; punctures shallow, fairly
sparse. Rostrum of female slightly curved, 1.5-1.6 times longer than
L23