Genus Pediasia

8 species in North America listed at All-Leps

wingspan 20-33 mm

larvae to 28 mm

Adult: forewing slender, variably brown to gray; hindwing broader than forewing, usually paler, and with prominent fringe of hair-like scales; labial palps project foreward, forming a "snout" (as in other members of this subfamily)

Larva: body pinkish-white to yellowish to light brown, often with paired dorsal and lateral spots on each abdominal segment; head yellowish-brown, brown, or black

all of United States and southern Canada

lawns, grassy areas; adults may fly low over lawns during the day, but are primarily nocturnal and attracted to light

adults fly from May to October

larvae feed on grasses (Poaceae)

sod webworms overwinter as young larvae a few centimeters below soil line among roots of weeds and grasses in silk-lined tubes; in early spring, larvae feed on upper root systems, stems, and blades of grass; they build protective silken webs, usually on steep slopes and in sunny areas, where they feed and develop; pupation occurs in May in underground cocoons made of silk, bits of plants, and soil; adults emerge about two weeks later, are erratic and weak flyers, live only a few days, and feed solely on dew; they rest in the grass or sometimes fly low over the ground during the day, but are primarily nocturnal, becoming active at dusk.

Eggs are deposited indiscriminately over the grass, and hatch in 7-10 days; the most severe damage to turf occurs in July and August when the grass is not growing rapidly; during this hot weather, larvae feed at night or on cloudy days; most species complete 2 or 3 generations per year, with approximately 6 weeks elapsing between egg deposition and adult emergence.

[adapted from text by North Carolina State U.]

other genera in the tribe Crambini (see MPG page)

live and pinned adult images of Pediasia trisecta by various photographers (Moth Photographers Group)

pinned adult image of Pediasia trisecta plus description, distribution, flight season, biology (Strickland Entomological Museum, U. of Alberta)

biology of webworms in general including Pediasia trisecta (North Carolina State U.)