A Natural Control for Iris Borers
May 12, 2017 | Common Garden Pests
Iris borers are the most destructive pest to irises, and can be a challenge to control. The iris borer larvae eat iris leaves and rhizomes and make plants susceptible to disease. Damage is typically first noticed in the spring as the larvae begin tunneling through leaves, often leaving streaks in the foliage.
Iris borer adults are a brown moth with a wingspan of about 2”. The adults are rarely seen as they are typically active at night. The larvae, which cause the damage, are pinkish in color and grow to about 2” long. The iris borer life-cycle is one year and consists of 4 stages; egg, larva, pupa and adult. Adults lay eggs in garden debris in late summer and early fall, where they overwinter. The larvae hatch out in early spring and feed until changing into pupae in mid summer. The pupae hatch out in about a month, at which time the new adults mate and lay their eggs.
Beneficial nematodes are an effective control for iris borer larvae in the soil. We suggest treating with Ecomask in late May or early June to kill emerging larvae. For more information on how to kill iris borers with beneficial nematodes, check them out in BioLogic’s Pest ID.