Most damage is caused by feeding on the surface of filling and maturing pods.
On the Prairies, diamondback moths are most frequently observed in canola fields. Other favoured food plants include broccoli, Brussels sprouts, cabbage, cauliflower, horseradish, commercial mustard, radish, and turnip. They also feed on stinkweed, shepherd's purse, and wild mustard. They are grey or brown, with light-tan marks on the margin of the forewing. While at rest, the wings are folded, roof-like, over the body.