Ottawa (Dunrobin), ON Canada

07 June 2003   12:57AM EST  (top left)
19/20 May 2003   (date of moth capture)  (top right)
20 May 2004   10:21PM EST  (bottom left and right)
The two bottom photos are of the same specimen.

Agrotis obliqua is one of seven species of Agrotis recorded from the Ottawa area (J.D. Lafontaine, pers. comm., 2001), five of which are illustrated on this website.  Having seen relatively few specimens, I find it somewhat difficult to distinguish Agrotis obliqua from specimens of Agrotis stigmosa (Hodges 10658) and Agrotis volubilis (Hodges 10659).  The specimen illustrated at top right represents one of the first records for this species in the Ottawa area, and was captured by Jim Troubridge in a UV trap on my front lawn.  My thanks to him and Dr. J. Donald Lafontaine of Agriculture Canada for confirming the identify of several specimens I later collected and gave to the Canadian National Collection in Ottawa.

Agrotis obliqua has a brownish forewing, with a slight reddish tone and, within my limited experience of Agrotis species, somewhat darker than Agrotis stigmosa.  Blackish shading along the costa extends nearly to the postmedial line and surrounds the orbicular and reniform spots; beyond the postmedial line, this shading is substantially reduced to non-existent.  Antemedial and postmedial lines have been quite well marked in the few specimens I have photographed, and specimens have usually had a dark median shade below the end of the reniform spot and parallel to the lower part of the pm line.  A narrow black dash extends from the base of the forewing to a short distance outside the am line.  The orbicular and reniform spots have a grayish filling, slightly paler than the surrounding dark costal shade.  In the subterminal area, there may be some dark tracery along veins, some sharp whitish points marking the location of the subterminal line, and some evidence of a dark patch about a third of the way along the outer margin below the apex.  The forewing fringe is reddish brown, similar to the ground color.  The thorax is brownish with somewhat paler tegulae.  The hindwing is a darkish gray-brown or brownish gray; the hindwing fringe is pale to whitish with a fine dark line in the fringe parallel to the outer margin.  

The fairly dark gray-brown hindwing is a useful aid for differentiating Agrotis obliqua from Agrotis volubilis, which has a whitish hindwing.  To distinguish Agrotis obliqua from Agrotis stigmosa, it is more useful to look at the differences in forewing color and pattern, Agrotis obliqua being darker in ground color, with more extensive dark costal shading, for example.  It is not always possible to differentiate these species without a thorough examination of the specimen, however.

According to Handfield (1999), the host plant for Agrotis obliqua is unknown. He indicates an adult flight season from the later part of May and possibly nearly to mid-July for my general area.

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