Pediasia trisecta and others
Lepidoptera: Pyralidae
Identification
• The caterpillar is gray or greenish, up to 1" long, slender, and
covered with brown spots. (a)
• The adult moth is 3/4" long, tan, and holds the wings close against
the body in a tubelike fashion. (b)
• When disturbed, the moth will fly in a dipping, zigzag pattern just
a few feet above the turf.
Damage
• The caterpillar emerges at night from a silk-lined tunnel in the
thatch and will eat grass blades down to the crown.
• Attacked turf has irregular brown areas because the grass blades
are gone, allowing the thatch to show. (c)
• Green, 1/8" diameter feces are numerous at the base of attacked turf.
• Damage usually occurs during dry periods of the growing season as
microsporidial diseases kill many of the larvae during wet periods.
Management
• Chemical insecticides are effective.
• Damaged turf usually recovers with irrigation (after the caterpillars
are controlled) because the undamaged crowns and roots are able to grow
new leaves.