Macronoctua onusta

Lepidoptera: Noctuidae

Identification
• The larva is a pinkish, fat caterpillar up to 2" long.
• Adult moth is purplish-brown, with a wingspan of 1-1¹/₂ ".

Damage
• Larva tunnels through the iris rhizome, causing damage and promoting rotting.
• Young larva tunnels down the iris leaf in the spring, causing water-soaked, yellow and brown streaks.

Management
• Removing and discarding damaged rhizomes and larvae helps control the damage.
• Insecticide application in the spring to the foliage when fans (young leaves) are 6" high is effective.

Other Information
• Tall-bearded iris is the most commonly attacked, but can survive moderate levels of infestation.
• Siberian, Louisiana, and other iris with smaller rhizomes are attacked less often, but an infestation usually kills the plants.