Species Nacerdes melanura - Wharf Borer

Nacerdes melanura (Linnaeus 1758)

9.4-13.5 mm(1)

adventive in NA, mostly New England to Great Lakes and along west coast; also in some inland sites - Map (1)(2)(3), native to the Old World (mostly Europe)

Moist wood, where the larvae build long galleries; wharf timbers between flooding and the high water level especially which were in badly decayed, well-riddled wood

adults emerge about the same time every year; active Apr-Aug outdoors (year-round indoors)(1)

wet and decayed wood (softwoods & hardwoods); adults feed on pollen(1)

Larvae feed almost entirely on very moist wood and can be destructive of pilings under wharves and buildings near water.(4)

usually one year (up to several years in cooler climates); mating and ovipositing occur in moist rotten wood, larvae develop in irregular galleries and pupate in small chambers; adults emerge in large numbers and live ~7 days(1)

They fly to light, often to windows; thousands may suddenly appear in/around a building, disrupt business operations and be a nuisance. Larvae may infest pilings under wharves and under buildings near the water, boardwalks along the sea coast, wood floors in damp basements, boats, greenhouse benches.(1)

Overwinter as adults inside buildings.(4)

Rhagonycha fulva has reddish-orange femora, dark antennae, and a different-shaped pronotum: