Wood borer species

Wood damaging pests can attack expensive antiques and even a building’s structural components. Wood pests have managed to develop an astonishing variety of life forms, and can even live comfortably in totally dry wood.

Bamboo Weevil

(Cyrtotrachelus longimanus)

Appearance

  • Dark brown body, plump, almost cylindrical, 2 to 3.7 mm in length. 
  • Antennae broaden at the tip, with the last 3 segments considerably larger and ending in well-defined antenna clubs. 
  • The humped thorax conceals the head and has teeth-like indentations in its rounded front. Two large dimples at the back of the thorax. 
  • Elytra (wing cases) are covered with small pits and bristly hairs.
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Lifecycle

  • The female lays 27–35 eggs into the food substrate, larvae hatch and bore into the plant. 
  • Larva undergoes up to 4 development phases and pupates inside the plant. 
  • The lifecycle can be as short as 60 days in good conditions (35 °C, 75% relative humidity) leading to multiple generations per year.

Habits

  • Larva feeds on bamboo cane, but the weevil is also known to breed on cassava root. 
  • Larva makes tubular passages along plant fibres and emerges leaving a perfectly round hole. 
  • This species from East Asia is brought in with cargo on ships (e.g. tapioca products), wooden packaging and even wooden musical instruments.

Woodboring Weevil

(Euophryum sp)

Appearance

  • Adults are 2.5 to 5mm in length. 
  • The weevils are reddish brown to black. They have a long snout, a cylindrical body and short legs. 
  • The larvae are a creamy white C-shaped, wrinkled and legless.
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Lifecycle

  • Eggs are laid singly by the female in specially evacuated holes. They are glossy, white, flexible and flattened at one end and they hatch within 16 days. 
  • The larvae tunnel in the wood for between six months and a year. They pupate near the surface for between two to three weeks. 
  • The adult emerges in the summer by boring its way leaving exit holes. The adults may live for over a year, causing further damage to the timber.

Habits

  • Damage is associated with damp and decaying wood, particularly timber already rotted by cellar fungus. Infestations can spread to adjacent healthy wood.

Powder Post Beetle

(Lyctus brunneus)

Appearance

  • Adults are 4–7mm in length. 
  • They are red brown, narrow and somewhat flattened.
  • The larvae are creamy white and measure 6mm when fully developed.
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Lifecycle

  • Whitish, long and cylindrical eggs are laid by the female into the wide pores of hardwoods. She lays between 30 and 50 eggs, which hatch in one or two weeks. They are laid only if the starch content of the wood is high enough for the larvae to feed. 
  • The larvae pupate for between two and four weeks near the surface. The adult emerges by biting its way out between May and September and throughout the year in heated buildings. 
  • The whole life cycle is normally less than one year.

Habits

  • Of the four distinct life stages, the larvae do the most damage to wood. Large quantities of adults are found on infested timber and window sills when they emerge. 
  • They are primarily pests of timber yards, but also cause considerable damage to furniture, sports equipment, wood block floors and joinery made of wide pored hardwoods.

Bark Borer

(Ernobius mollis)

Appearance

  • Adult – 3–6mm. Red or chestnut brown with yellow silky hairs on body.
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Lifecycle

  • Female lays 20-30 eggs in bark crevices which hatch into larvae in two to three weeks.
  • Pupation follows in spring or early summer, lasting one or two weeks.
  • Adults emerge between May and August.

Habits

  • Damage confined to unbarked softwoods, causing no structural damage. Occurs on pergolas, rustic work, fence posts and garden sheds.

Common Furniture Beetle

(Anobium punctatum)

Appearance

  • Adult 3–4mm in length. Thorax is significantly humped concealing the head. 
  • Larva – usually concealed in wood.
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Lifecycle

  • The adult female will lay up to 80 eggs in cracks or old flight holes in timber and dead trees. 
  • The larva will live for 3 to 5 years boring through the timber before emerging to breed.

Habits

  • Not regarded as a pest of stored products, but is timber related. 
  • Infests both hardwoods and softwoods. 
  • Flies actively in warm sunny weather.

Steely Blue Beetle

(Korynetes caeruleus)

Appearance

  • Adult – 4mm. Shiny blue colour.
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Lifecycle

  • Eggs are laid on the surface of wood by or just inside exit holes. 
  • Larvae live inside wood that has been infested by woodboring insects, where they feed on the larvae of these wood-damaging insects. 
  • Adult: After emergence they mate, lay eggs and then die.

Habits

  • Predator of common furniture beetle and deathwatch beetle – so its presence indicates a heavy infestation of either woodboring insect. 
  • It is the rarely seen larvae which consumes the larvae of the woodboring pests in their tunnels. The steely blue beetle is not capable of damaging wood.

Deathwatch Beetle

(Xestobium rufovillosum)

Appearance

  • Adults are 5 to 7mm in length; larvae - 10mm. 
  • The beetles are dark reddish brown and have yellowish scale-like hairs on the upper body and wing cases. The larvae are a creamy white hook-shape covered in erect golden hairs with dark brown jaws on its head.
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Lifecycle

  • After mating, the female lays 3-4 eggs clustered in cracks of rough wood surfaces. They are whitish, oval shaped and she lays between 40 and 60 during her life. The eggs hatch within two to five weeks. 
  • The larvae pupate just below the surface of the wood. The adult emerges in early summer by gnawing through the surface and leaving the characteristic exit holes.

Habits

  • In its natural environment the insect lives in the dead wood of several species of hardwood trees where fungal decay has set in. 
  • Within buildings the insect occurs almost entirely in old hardwood, in particular large oak timbers. 
  • The larvae do the most damage, as they tunnel in the wood for between five and ten years.

Wharfborer

(Nacerdes melanura)

Appearance

  • 7–14mm in length. 
  • Yellow brown with tips of elytra (wing case) black. 
  • 3 ridges along the length of the elytra.
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Lifecycle

  • Eggs are laid on damp, decaying timber. 
  • Larvae bore through wood for about 9 months then emerge in Summer.

Habits

  • Larvae require wood to be constantly wetted so that fungi break down the wood fibres. 
  • Two main sources of infestation in buildings — structural timbers where rainwater leakage occurs, and pieces of timber buried below concrete foundations, paths and pedestrian precincts.

House Longhorn Beetle

(Hylotrupes bajulus)

Appearance

  • Adults: 8 to 25mm in length. 
  • The beetles are black or brown and covered with greyish hairs on the upper body and wing cases. There are two shiny black spots on the thorax which resemble eyes. 
  • The fleshy larvae are greyish white and can grow to 35mm when fully developed.
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Lifecycle

  • The female lays eggs in summer to early autumn in cracks and crevices of wood. They are yellowish to greyish white, elliptical with pointed ends, and hatch in two to three weeks. 
  • The larvae do the most damage, as they tunnel in the wood for between three and eleven years. 
  • The larvae pupate near the surface of the wood and adults emerge after approximately three weeks.

Habits

  • It infests seasoned or partly seasoned softwoods. It usually damages sapwood but heartwood can also be affected.
  • Isolated infestations occur in other parts of the country from imported infested packaging cases.