Sod webworms in lawns
Sod webworms spend the day in silk-lined tunnels in the thatch and come up at night to clip grass blades, so they are exactly the moving, near-surface target the ambushing nematode S. carpocapsae suits. UC IPM calls it a valuable control. Apply it late in the day, not at midday, onto moist but not soggy soil, water it in straight away, and irrigate several times over the next two weeks. UMass warns that it is very vulnerable to drying out.
At a glance
- Damage
- Small ragged brown patches; grass blades notched and clipped
- Type
- Chewing
- Settings
- Garden
- Threshold
- 15 larvae per yd² (UC IPM); Minnesota tolerates up to 12 per ft²
- Release
- Steinernema carpocapsae
- Rate
- 25 million S. carpocapsae per 1,000 ft² (about 270,000 /m²), onto warm, moist soil (UC IPM)
How to confirm it
Part the grass at the edge of a small brown patch: blades notched or clipped off, silk-lined tunnels in the thatch, and green, pellet-like frass. A soap flush brings up slender, greyish caterpillars up to 1 inch (2.5 cm) long with rows of dark spots.
Identification, lifecycle, degree days and every control option are on the full Sod webworms profile. Not sure it is this pest? Answer four questions about the damage.
Work it out
How many do I need?
Carries Steinernema carpocapsae and lawn & turf through so nothing is re-entered. Open the calculator →