Billbug damage in lawns
Billbug damage in cool-season lawns is a slow-developing mystery. The adult weevils move through lawns in spring without visible damage; the eggs hatch in June; the larvae feed quietly underground through July and August; and the damage finally shows in August as dead patches that look like drought.
Billbug damage in cool-season lawns is a slow-developing mystery. The adult weevils move through lawns in spring without visible damage; the eggs hatch in June; the larvae feed quietly underground through July and August; and the damage finally shows in August as dead patches that look like drought stress but don't recover when watered. By the time the visual symptoms appear, the feeding is nearly done.
Species and distribution
Per Rutgers NJAES, several billbug species damage lawns in the United States:
| Species | Primary range | Preferred host |
|---|---|---|
| Bluegrass billbug (Sphenophorus parvulus) | Northeast, Midwest | Kentucky bluegrass, perennial ryegrass |
| Hunting billbug (Sphenophorus venatus vestitus) | Southeast, Midwest | Zoysiagrass, Kentucky bluegrass |
| Denver billbug (Sphenophorus cicatristriatus) | Great Plains, mountain west | Kentucky bluegrass, tall fescue |
| Phoenix billbug (Sphenophorus phoeniciensis) | Southwest | Bermuda grass |
Billbugs are weevils (Coleoptera: Curculionidae). Adults are 0.5—0.75 inches long, dark brown to black, with a characteristic curved snout (the "bill").