Wood-boring Weevil – Pentarthrum huttoni
General: Decayed softwoods and hardwoods in damp conditions – poorly ventilated ground floors, cellars, and wood in contact with damp solid floors or walls are particularly susceptible. Damage secondary to fungal decay. Also attacks plywood in these conditions.
Emergence holes: Small, ragged, about 1 mm diameter.
Tunnels: Numerous, normally in the direction of the grain. Often break through to wood surface.
Bore dust: Fine, gritty.
Likely miss-identifications: Common furniture beetle.
- No insecticide treatment required.
- Remove source of dampness and dry out sound timber.
- Replace decayed timber.
- Infestation of sound dry wood not possible.
Insect Characteristics and Location:
Some 2 – 5 mm in length, black brown or red brown in colour. The females bite holes in wood and lay a single egg in each covered in white secretion. The larva consume their ‘shell’ and burrow into wood. These white larva grow to about 3.3mm in length.
The Pupal chamber is lined with the hyphae of fungus (hyphae being the thread like filaments from germinating spores). Pupa are approximately 3 – 5mm in length.
Eggs hatch after about 16 days, larva pupate after 6 – 8 months. Pupal stage lasts about 16 days, the adult life span about 16 months.
Many weevils will mate within wood without requiring emergence. Commonly they infest plywood of oak and birch.
The fungus associated with its life cycle is usually the cellar fungus ‘coniophora cerebella, often a cause of wet rot.