Iris borers are the larvae of a brown moth with a wingspan of about 2”. The adult moths are rarely seen as they fly at night. The larvae are pinkish in color and grow to about 2” long. The larvae eat iris leaves and rhizomes, and are the most destructive pest of irises. The iris borers’ 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 larva 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. The larva can be extremely destructive to iris plants, and can quickly kill and entire established iris plot by eating the rhizomes and leaving them susceptible to bacteria and fungus.