What's eating my iris 'black gamecock'?

Iris louisiana 'Black Gamecock' is a water-margin Louisiana iris. Its moist growing conditions attract slugs and snails heavily. Iris borer is a serious US threat. Aphids cluster on stems and thrips may scar the dark petals. Unlike bearded iris, Louisiana irises tolerate wetter soil, but this also increases slug pressure significantly.

Caterpillars tunnel into leaves then down into rhizomes, causing water-soaked streaks and leading to rhizome collapse and bacterial rot. Clean up all foliage in autumn to remove overwintering eggs. Apply beneficial nematodes to moist soil in spring. Squash larvae in leaves when spotted.

Heavily chewed leaf fans and stem bases; very common in the boggy or pond-margin conditions this iris prefers. Iron phosphate pellets (safe near water); hand-pick at night; avoid excess mulch that provides slug refuge near the crowns.

Colonies on stems and flower buds cause stickiness, leaf curl, and can spread viral diseases. Dislodge with water jets; apply insecticidal soap; introduce beneficial insects such as ladybirds and parasitic wasps.