What's Eating Your Canna Lily?

Pale green caterpillars 1 to 1.5 inches long with a yellow-brown head, hidden inside the tightly rolled new leaf at the top of the canna stalk. The moth lays eggs in the unfurling leaf, and the caterpillar stitches the edges together with silk as it feeds inside.

New leaves never unfurl, stay rolled like cigars, and unfold into ragged shredded strips with rectangular holes punched in rows. Heavy infestations defoliate the plant within weeks and stop flower spikes before they emerge. The Lesser canna leaf roller is the dominant species across the southeast and Gulf Coast.

Stocky metallic copper and green beetles, half an inch long, often clumped on a single leaf with smaller beetles climbing the cluster. Adults are most active on warm sunny mornings from late June through early August across the eastern and midwestern US.

Adults skeletonize canna's broad paddle leaves, leaving only the network of veins behind, and chew ragged holes in the bright flower petals. Damage often starts at the top of the plant and works downward. Plants survive but the season's flower display is ruined.

Soft pear-shaped insects 2 to 3 mm long, in green, black, or grey, packed on the unopened flower spike and the soft new shoot tips. They concentrate where canna's leaf sheath meets the stalk and cling to bud clusters before the flowers open.

Flower buds drop without opening, and the spike often emerges deformed with twisted bracts. Sticky honeydew coats the lower leaves and draws sooty black mold. Aphids also vector canna mosaic virus, which streaks the leaves with yellow and reduces vigor permanently.

Specks barely larger than a pinhead, in tan, red, or pale yellow, clustered on the underside of canna's broad paddle leaves. Fine webbing collects in the leaf-sheath joints where the leaf wraps the stalk. A sheet of white paper held under a tapped leaf catches them.

Leaves show pale stippling along the veins, fade to a dusty bronze, and drop from the lower stalk upward. Damage is worst in hot dry weeks of July and August, especially on cannas planted in full sun with reflected heat from a wall or paving.

Soft-bodied brown or grey mollusks, 1 to 4 inches long, active overnight and on cool damp mornings. They hide under canna leaf litter, the leaf-sheath joints, and beneath mulch by day. Silvery dried slime trails on the stalks and lower leaves are the most obvious sign.

Large ragged holes appear in the soft spring growth overnight, often along the leaf edges and on the new shoots emerging from the rhizome. Heavy slug pressure shreds the first flush before it can open, leaving the plant looking torn even after it grows out.