Controlling Sod Webworm (aka “Lawn Moths”)
Most of the turf damage is caused by the larvae (caterpillars)—not the adult moths.
What they look like
Sod webworms (often called “lawn moths”) are buff-colored moths about ½ to ¾ inch long as adults. When resting, they fold their wings tightly around the body, giving them a narrow, cigar-like shape. They commonly fly when disturbed in the late afternoon.
The larvae are gray to tan with small dark spots and brown heads, reaching ¾ to 1 inch when fully grown. These caterpillars are the stage that chews grass and creates the visible damage.
When infestations show up
Infestations can develop quickly. They may start in spring but often become obvious in summer when turf is already under heat or watering stress. In our experience, outbreaks can be especially common on new sod installations.
How to spot an infestation
An early sign is seeing small moths “zig-zagging” over the lawn at dusk. If you suspect sod webworms, inspect the turf closely for these indicators:
- Small patches of grass chewed off at ground level
- Fresh clippings near damaged areas
- Green fecal pellets (frass) in and around the damaged turf
- Larvae, silken tubes, or webbing in the thatch layer and top inch of soil
If you choose to use an insecticide
If insecticides are used, preparation and timing make a big difference:
- Mow first and remove clippings to help the product reach into the turf canopy.
- Irrigate thoroughly before application (about ½ to ¾ inch) to bring webworms closer to the surface.
- Apply in the late afternoon or early evening when larvae are active.
- After application, lightly irrigate (about ⅛ inch), and avoid heavy watering for 24–48 hours unless the label instructs otherwise.
- For granules, lightly water immediately after application to rinse granules off blades and activate the product.
Always follow the label directions. Do not overdose thinking it will work better. Often multiple applications are needed, commonly spaced at about 7-day intervals, to target larvae and newly emerging stages.