Ottawa (Dunrobin), ON Canada

10 August 2000   12:07AM EST  (top left)
9 June 2002   9:59PM EST  (top right)
4 June 2001   10:02PM EST  (bottom left)
4 June 2001   10:00PM EST  (bottom right)

The two photos at bottom are of the same specimen.

When its wings are closed, the striking pattern of Nerice bidentata is somewhat reminiscent of those trompe l'oeil silhouette figures that can be seen either as an outline of an urn or as facing profiles of two people.  The double-toothed aspect that has given rise to this species' name refers to the dark teeth of the dark brown to black band running the length of the forewing.  The area of the forewing nearest the inner margin is a lighter gray-brown color, often edged with white which heightens the contrast with the dark teeth.  Towards the costal edge and apex of the wing, the color is paler, and there is a dark blotch in the subterminal area following the mark that indicates the beginning of the postmedial line.  At the outer margin, in the subterminal area, there is a jagged triangle of gray-brown edged on the upper side with black.  The hindwing is brown.  At rest, Nerice bidentata may hold its folded wings fairly flat (top left), or may pull them into a peaked-roof shape (bottom left).

The host plant of Nerice bidentata is elm.  According to Handfield (1999), this species appears to have two generations per season in my general area, the first appearing from mid-May through June, and the second appearing in July through August.  

I have photographed this species in 2000 on 30 July and on 10 August; in 2001 on 21 and 25 May, and on 4, 12, 20 and 21 June; in 2002 on 1, 8, 9 and 19 June, and on 24 July.