Surface Feeders - Tropical Sod Webworm (TSWW)

TROPICAL SOD WEBWORM (TSWW)
scientific name: Herpetogramma phaeopteralis
Similar species: Subterranean Sod Webworm

FIELD KEYS
Hosts: bermudagrass, St. Augustine, Kikuyu-grass, centipedegrass, zoysiagrass, bahiagrass
Site symptoms: Small areas of thinning turf turn off color and increase in size daily. These smaller, unkempt looking patches coalesce into larger areas of thinning brown turf. Birds feed on affected areas leaving peck holes and small moths can be seen flying low over turf at dusk.
Plant symptoms: Above-ground plant structure shows damage from insect feeding activities that range from skeletonized upper and lower leaf surfaces to complete leaf consumption with some silken webbing. At pupation, unlike cool-season species, larvae can spin cocoons made of webbing, plant parts, and soil.
Site keys: Sunny to transitionally shaded well-managed sites.

SPECIMEN ID
Immatures are cream-colored segmented worms with yellow brown heads that range from 1/3 inch long at hatch to 3/4 inch long when fully grown. Adults are dusky brown moths with 3/4 inch wing spans and a wedge or arrowhead-shaped appearance at rest.

SCOUTING TIPS
Like other SWW species the presence of adults flying at dusk is definitive, it may not correlate to treatable larval populations. Adult TSWWs feed on nectar and other sweet food sources, so they also can be seen in flowering or fruit bearing shrubs or trees near infested sites. Once adults have been seen, monitor larval populations with soap or insecticidal flushes beginning about two weeks after peak adult activity. Turf can vary widely in its ability to tolerate higher populations of TSWW, but sites with consistently warm temperatures and high humidity or rainfall frequently suffer greater feeding damage. Larval damage at infested sites can be similar to armyworm damage - where actively feeding high larval populations can literally mow down grass.

CONTROL STRATEGIES
Cultural: Manage turf for vigorous growth. Overseed or renovate damaged areas with high-endophyte regionally-appropriate grass species or varieties that show tolerance, like common bermudagrass. Because TSWW is a true warm season species and because it has a relatively short life cycle, once it has been identified at a site, managers should maintain a consistent scouting regimen.
Chemical: Where scouting is ongoing, correlate larval population data with observed damage to develop site specific treatment thresholds. If this information is not available, consider control applications once damage has been observed.

Growth stages: egg - larva (up to eight instars)* - pupa - adult
*- treatable stages

Life cycle: 1 year life cycle (multiple generations)
Sequence: larva - pupa - adult - egg - larva