Pest identification
What's eating my iris versicolor?
Iris borer (Macronoctua onusta)
Signs: Caterpillar tunnels downward through leaf midribs into rhizomes, causing foul rot and plant collapse
Control: Remove and destroy all old foliage in autumn to eliminate overwintering eggs. Apply Steinernema carpocapsae nematodes to soil in spring; dig and discard infected rhizomes.
Iris sawfly (Rhadinoceraea micans)
Signs: Grey-blue larvae shred leaf margins into ribbons from late spring
Control: Hand-pick larvae into soapy water from late April onward. Inspect leaf undersides weekly.
Slugs and snails
Signs: Holes in young foliage and slime trails on leaf bases near water
Control: Use iron phosphate pellets safe near ponds; collect at dusk. Avoid overwatering surrounding soil.
Aphids
Signs: Honeydew and sooty mould on stems; distorted flower buds
Control: Encourage natural predators; spray with insecticidal soap, keeping product away from open water.
Keep iris versicolor pest-free
Healthy plants resist pests best. Get the basics right:
Iris versicolor pests — FAQ
What is eating my iris versicolor?
Blue flag iris (Iris versicolor) faces its worst threat from iris sawfly larvae that strip leaves to tatters in spring. Iris borer is a serious US pest tunneling into rhizomes. Slugs attack soft growth at the water's edge, and aphids colonize flower stalks through summer.
How do I get rid of iris borer (macronoctua onusta) on iris versicolor?
Caterpillar tunnels downward through leaf midribs into rhizomes, causing foul rot and plant collapse Remove and destroy all old foliage in autumn to eliminate overwintering eggs. Apply Steinernema carpocapsae nematodes to soil in spring; dig and discard infected rhizomes.
How do I get rid of iris sawfly (rhadinoceraea micans) on iris versicolor?
Grey-blue larvae shred leaf margins into ribbons from late spring Hand-pick larvae into soapy water from late April onward. Inspect leaf undersides weekly.
How do I get rid of slugs and snails on iris versicolor?
Holes in young foliage and slime trails on leaf bases near water Use iron phosphate pellets safe near ponds; collect at dusk. Avoid overwatering surrounding soil.
How do I get rid of aphids on iris versicolor?
Honeydew and sooty mould on stems; distorted flower buds Encourage natural predators; spray with insecticidal soap, keeping product away from open water.