Sod webworm (Pediasia trisecta)
Pest description and crop damage Sod webworm are larval caterpillars that are 0.5 to 0.75 inch in length and feed on turfgrass foliage. Sod webworm are light green or yellow with dark patches across the back and sides, and a dark brown head.
Larvae construct sink or web lined tunnels through the thatch layer resulting in the name sod "webworm". Larval cutworm populations build as the summer progresses and damage typically occurs in the late fall or early winter when turfgrass growth slows, and larvae continue to feed. Damage includes brown patches and shredded grass blades.
Biology and life history The sod webworm overwinters as larvae in the soil and emerge as adults in the spring. Eggs are laid on host plants, and hatch after a few days. Larvae burrow through the thatch layer making a web lined tunnel and feed on turfgrass foliage.
Scouting and thresholds Scouting for larvae should begin in the spring and continue to the onset of cold weather. Thresholds for larval numbers have not been established in the PNW. Scout using a tablespoon of lemon scented dish soap in a five-gallon bucket of water. Apply the mixture and wait for 5 minutes. Larvae will emerge from the thatch trying to escape the dish soap application
Management-biological control
- Bacillus thuringiensis-Some formulations are OMRI-listed for organic use.
- beneficial nematodes
Management-chemical control
Products for home use
- bifenthrin-Restricted use
- carbaryl
- deltamethrin
- fenvalerate
- gamma-cyhalothrin
- indoxacarb
- lambda-cyhalothrin
- permethrin
- plant essential oils-Some formulations are OMRI-listed for organic use.
- pyrethrins-Some formulations are OMRI-listed for organic use.
- tetraniliprole
Products for commercial use
- acephate
- azadiractin-OMRI-listed for organic use.
- beta-cyfluthrin
- bifenthrin-Restricted use
- bifenthrin + imidacloprid-Some neonicotinoids have been banned from use on public properties.
- carbaryl
- chlorantraniliprole
- clothianidin-Some neonicotinoids have been banned from use on public properties.
- clothianidin + bifenthrin-Restricted use
- cyantraniliprole
- cyfluthrin
- cypermethrin
- deltamethrin
- dinotefuran-Some neonicotinoids have been banned from use on public properties.
- esfenvalerate + prallethrin + piperonyl butoxide
- gamma-cyhalothrin
- indoxacarb
- lambda-cyhalothrin
- methomyl
- mint oil, geraniol + oil of rosemary-OMRI-listed for organic use.
- spinosad-Some formulations are OMRI-listed for organic use.
- thiamethoxam-Some neonicotinoids have been banned from use on public properties.
- trichlorfon