|scientific name Besma endropiaria |
common name Straw Besma
No information available for Alberta; flies in spring and early summer elsewhere.
A thin-winged and finely marked geometrid. Ground colour pale tan, with a fine, straight PM line (sometines absent on hindwing) and a scalloped (sometimes absent) subterminal line. Both fore and hindwings are characterized by a well-defined pointed projection mid-way along the margin. Lambdina fiscellaria is similar, but lacks the scalloped subterminal line (often more clearly visible on the underside), and flies in the fall.
Virtually identical to B. quercivoraria in colour and pattern; according to Forbes (1948), endropiaria has translucent rather than opaque wings and lacks the discal spot. B. endropiaria and B. quercivoraria are treated as the same species by McGuffin (1987) since there are no apparent morphological differences. In eastern North America there are however differences in broodedness, quercivoraria producing two annual broods and >endropiaria one (Wagner et al. 2001). The Alberta records may be in error, see below.
The larvae are green-yellow with reddish highlights, mimicking the leaf petioles and twigs of maples. The pupa overwinters (Wagner et al. 2001).
Not of concern.
Larvae prefer maples (Acer spp.) but also feed on alder birch (Betula)and oak (Quercus) (Wagner et al. 2001).
Eastern North America west to Saskatchewan; it is unclear if this species occurs in Alberta, our populations may all be referable to B. quercivoraria. The only Alberta records for endropiaria are based on Bowman's (1951) records, but all Besma specimens in the Bowman collection appear to be quercivoraria.
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