Ottawa (Dunrobin), ON Canada

10 June 2003  9:49PM EDT

Balsa tristrigella is one of three species of Balsa known to occur in the Ottawa area, and the one most commonly seen at my location.

The forewing of Balsa tristrigella is light gray tinged with brown toward the outer margin, mostly covered with very fine black lines running lengthwise.  The antemedial line is distinct only at the costal edge, and the basal area is not noticeably separated from the median area.  At the costal edge, the postmedial line is observable as two blackish lines angled towards the outer margin; the inner of these two lines is heavier and straighter than the outer one.  The pattern of fine black lines is heavier towards the outer margin.  Although the common name of this moth is the Three-Lined Balsa, it might more accurately be called the many-lined balsa, unless the three lines referred to are the am and double pm lines at the costal edge, or lines on the larva.

The larvae of Balsa tristrigella feed on hawthorn (Covell, 1983).  According to Handfield (1999), the adult flight season in my general area is from about the end of May to mid-July.

I have photographed this species in 2000 on 17 June; in 2001, on 21 and 26 May, and on 2 and 22 June; in 2002, on 31 May, and on 7, 13 and 23 June; in 2003, on 27, 28 and 30 May, on 10, 14, 20, 21, 22, 23 and 25 June, and on 1 July.