Bluegrass webworm

The Bluegrass webworm (Parapediasia teterrella) is a member of the order Lepidoptera and the family Crambidae. This insect is widely recognized as a destructive pest that specifically targets turfgrasses and various grass species in managed landscapes, residential lawns, and golf courses.

The primary hosts for this pest include a variety of cool-season grasses such as Kentucky bluegrass, fescue, and ryegrass. Beyond lawns, these caterpillars can occasionally impact cereal crops when the pest population reaches high densities, leading to significant economic losses in agricultural regions adjacent to grassy areas.

The biology of Parapediasia teterrella involves a life cycle consisting of egg, larva, pupa, and adult stages. The larvae are nocturnal feeders, constructing silk-lined tunnels within the thatch layer or the upper soil profile. They emerge at night to feed on grass blades and stems, retreating into their shelters during daylight hours.

Symptoms of infestation typically appear as irregular patches of yellow or dead grass that look like drought damage. However, closer inspection reveals that the grass blades are chewed off near the soil line. Because the larvae feed on the crown, affected areas can be easily pulled away from the soil, confirming the presence of the webworm.

Effective management requires a combination of cultural and chemical tactics. Key control measures include:

• Maintaining proper turf health through adequate fertilization and irrigation.
• Regular dethatching to remove the habitat for larvae.
• Using biological control agents such as nematodes or Bacillus thuringiensis (Bt).
• Applying systemic or contact insecticides during peak larval activity to suppress populations.