Spring can bring out more than just the blossom on the trees and the flowers in the garden. Adult woodboring beetles start to emerge from about April, making round or oval shaped holes in timber, leaving sharp edges. These are known as ‘flight holes’ and can be seen with the naked eye.
The woodboring beetles can often be seen on windowsills – attracted to the light. However, it’s the larvae (or woodworm) of these beetles, that we don’t often see that can damage anything from furniture and floorboards to joists and structural timbers.
In general woodboring beetles will not lay their eggs on polished, planed or painted surfaces (as they are exposed) but will deposit them on rougher areas of timber with crevices. If the timber is damp, it is more likely to be attacked as it may be softened by fungal decay.
As soon as the eggs hatch the woodworm burrow deep into the wood and dependant on the species will remain hidden within the timber for 3 – 5 years. All that time munching their way through the wood and weakening it.
The type of timber attacked will vary between woodworm species. Wood in the growing tree consists of two parts, the dense heartwood in the centre and the live sapwood on the outside. It is the softer sapwood that is infested by insects first. The hard heartwood can only be attacked by some beetle species, and often only after it has become damp and decayed by fungi.
Timber can be further separated into hardwoods (Oak, Ash, and Beech for example) and softwoods (such as Pine, Douglas Fir and Spruce). Some species of woodboring beetles have a preference for attacking a particular type of timber, while others are not so fussy:
- Common Furniture beetle – attack’s both hardwoods and softwoods, plywood and wicker-work, so can be found in most properties in the UK where conditions are suitable.
- Woodboring Weevil – only attack timber which is damp and decayed such as skirting’s and joists in contact with damp walls.
- Deathwatch beetle – usually only attack’s decayed hardwoods, so it is mainly found in older timber framed properties. Once established, an infestation can spread to undecayed hardwood and attached softwoods, albeit slowly.
- Powderpost beetle – only attacks the sapwood of wide pored hardwoods such as oak. It has become more common in recent years due to the increased use of “green” oak and some far-eastern plywood’s.
- House Longhorn beetle – does a considerable amount of damage to the sapwood of softwoods, but is currently limited to the South East of England.
If you should find fresh flight holes, bore dust (frass) below timbers or small beetles on windowsills, it is sensible to request a Certificated Surveyor in Remedial Treatment (CSRT) to complete a woodworm survey. This will assess the extent of any problem, the type of woodboring beetle involved and offer recommendations on the most targeted and effective treatment to control woodworm before it can spread any further.