Ottawa (Dunrobin), ON Canada

18 August 2006   9:21PM EST  (top left and right)
10 August 2006   1:11AM EST  (bottom)
The first two photos are of the same specimen.

Eucosma similiana is one of about a dozen species of Eucosma that have been recorded from the Ottawa area (J.D. Lafontaine, pers. comm., 2001).  My initial identification of Eucosma similiana was based on Internet resources.  Subsequently the identity of one collected specimen was confirmed by Dr. Jean-François Landry of Agriculture Canada, to whom my thanks; this specimen was given to the Canadian National Collection in Ottawa, and also used in the All Leps Barcode of Life project of the Biodiversity Institute of Ontario at the University of Guelph.  Some additional information has been gleaned from Forbes, William T.M., The Lepidoptera of New York and Neighboring States, Primitive Forms, Microlepidoptera, Pyraloids, Bombyces (Ithaca, New York: Cornell University, 1923), where the name was given as Eucosma similana.  There appears to have been some issues over the naming of this species, at one time considered a subspecies of E. dorsisignatana, but if I have properly understood the references I have found, the correct current name appears to be Eucosma similiana.

Eucosma similiana has some similarity to E. dorsisignatana (Hodges 3116), but is in my experience more brownish than gray in the ground color of the forewing.  The prominent dark brown markings of E. dorsisignatana are fused, in E. similiana, to form a single, thick, somewhat rounded L-shaped mark on each wing.  When I look at the moth from above, in resting position with wings closed, I see the marks of the two wings forming a sort of omega shape (see photo at top right).

According to Forbes (1923), the adult Eucosma similiana flies in August.  He gives no information as to host plants.

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