Ottawa (Dunrobin), ON Canada

16 September 2006   7:51PM EST  (top left)
16 September 2006   9:32PM EST  (top right)
14 September 2006   9:01PM EST  (bottom left)
17 September 2006   8:55PM EST  (bottom right)

Eucosma dorsisignatana is one of about a dozen species of Eucosma that have been recorded from the Ottawa area (J.D. Lafontaine, pers. comm., 2001).  My identification of Eucosma dorsisignatana is based on Internet resources and on the description of this species in Forbes, William T.M., The Lepidoptera of New York and Neighboring States, Primitive Forms, Microlepidoptera, Pyraloids, Bombyces (Ithaca, New York: Cornell University, 1923).  This species is also included in Covell, Charles V., Jr. A Field Guide to the Moths of Eastern North America. (Boston: Houghton Mifflin (Peterson Field Guide Series), 1984).

The forewing of Eucosma dorsisignatana is described by Forbes (1923) as dark ash-gray, with a very slight violet gloss.  The markings are dark brown, partially to completely outlined by fine whitish lines.  The innermost mark forms a half-ellipse extending from the inner margin about halfway up the wing, straight edge of the half-ellipse along the inner margin.  Just past the midpoint of the wing, a second dark brown mark forms another half-ellipse, this time with the curved end just touching the inner margin, and fading out shortly below the costal edge of the wing.  Some specimens also show a fainter brown fascia from the costa to the outer margin just above the anal angle; this mark is visible in the specimens on the left above.  There may also be a small, faint brown patch at the apex.  Forbes (1923) indicates a wingspan of 12 to 20 mm.

According to Forbes (1923), the larva of Eucosma dorsisignatana feeds on the roots of goldenrod, and the adult moth flies in September.

My records to date for Eucosma dorsisignatana (each date representing "the night of") are in the table below: