Borers

Borers are pests of wood and damage may sometimes be mistaken for termite damage.

Growing trees are protected by the bark covering and have a defense system of:-

Borer Damage Image 1

  • Kino
  • Resin
  • Various Latex Substances.

These defence systems may prevent insects entering and in many cases stop the infestation.

Once a tree is felled the tree stops producing defensive material and the sap cannot engulf its enemies.

To prevent freshly felled logs from being attacked they must be dried out and utilised quickly.

Kiln Drying:Borer Damage Image 2

  • Reduces moisture content.
  • Kills any insects present.
  • No longer susceptible to pests of moist wood.

It is important for pest controllers to be aware of the appearance of moist timber damage so it may be distinguished from dry timber pests.

Reproduction & Life-cycle:

Adult females lay approximately 70 eggs during their life-time. The female bites wood and lays 1-3 eggs in the incision. The eclosion period is 6-15 days. Larvae are white and C-shaped (scarabaeiform) with large spiracles on the 8th abdominal segment. The larval stage is 2 months to 1 year and is dependent on temperature, humidity and the starch in sapwood. Mature larvae tunnel toward the surface of the wood and excavate an oval cell for pupation. The pupal stage is 12-27 days. Adults live 78-300 days.

Symptoms of Infestation:

  • Holes of various shapes and sizes on the wood surface
  • Borer dust ejected or falling from holes, forming small piles on or beneath timbers
  • Tunnels beneath the surface which can be exposed by wear or sanding back of floorboards or by probing
  • Larvae which can be found by probing
  • Surface irregularities or rippling of paint due to insect activity beneath the surface of the wood - commonly termites
  • Chewing or tapping noises in timber common with longicorn and jewel beetles

Important Indicators for Borer Identification:

  • Is the timber a hardwood or a softwood and is there sapwood and/or heartwood present?
  • Is the timber seasoned or unseasoned?
  • What is the texture, colour and consistency of the borer residue or sawdust ?
  • The size, shape and numbers of emergence holes present , if any
    • Calymmaderus, round to irregular (1-2mm)
    • Prospheres, slightly oval (3-5mm)

Unseasoned (Green) Timber Borers:

  • Infest standing trees (stressed), freshly felled logs or green timber-in-service
  • Will die if kiln-dried or possibly emerge during air-seasoning but can also carry over to timber-in-service
  • They cannot re-infest seasoned timber

Examples of Green Timber Borers:

Seasoned Timber Borers

© Copyright Tony DiBetta 2007