Combating wood pests (woodworms)
Wood pests attack wood used in constructions as well as pieces of furniture. Any building or installation made of natural wood, either indoor or outdoor, is at risk to be infested by wood pests. Wood-damaging insects prefer different types of wood. Some are looking for hardwood such as eucalyptus, oak or ash, others damage only softwoods such as cedar, pine or fir. Other important factors for an infestation are the moisture content, age and availability of the wood.
In our latitudes the most encountered wood pests are the Longhorn beetle, or House borer, the Powderpost beetle, which is also known under the name Parquet beetle, the Common and the Pied furniture beetle as well as carpenter ants and termites. Wood pests are called preferably those organisms that are capable of damaging or destroying wood. The damage of the timber occurs during the feeding of the insects or in the creation of a living and breeding ground. What in nature, like in forests, is a useful procedure, can become a problem in our areas of life.
The House borer / Longhorn Beetle
The House borer, or Longhorn beetle, is a brown-black to black beetle. It is probably the most common wood pest in Europe. The House borer females are between 10 and 25 mm long, the male barely 8mm. The white larvae of the House borer can reach a length of up to 30 mm and a diameter of up to 5mm. The larvae live in younger, up to 50 years old softwood and can cause major structural damage, such as in roof beams and rafters.
By means of a long ovipositor the females lay their eggs deep in cracks and bumps in the wood. After 2 to 3 weeks the larvae (woodworm) hatch and bore into the wood. So they devour increasing tunnels with diameters up to 12 mm in the wood. Temperatures of 25°C and a humidity inside the wood of 40 to 50% offer the larvae optimal living conditions. A Longhorn beetle infestation can be recognized by the oval shape of the exit holes. These holes are drilled by the bugs already as larvae and the surface is sealed afterwards until they use the holes to leave the wood as adult insects. The holes have a size of 5 to 10 mm in longitudinal diameter. Characteristic are also the rasping sounds of feeding larvae.
Because of the long development time of larvae (depending on the living conditions from 2 up to 10 years) an infestation is discovered too late in the most cases, usually with the emergence of the exit holes. The wood can then already largely hollowed out and the load capacity of e.g. roof beams can be significantly reduced. A permanent control of roof trusses is therefore advisable, both as by visual inspection (as well on the top of the beams) and by knocking (sounds hollow when infested by pests) and by "eavesdropping" on feeding sounds of the larvae on warm days.
The house is prepaired for a surface treatment of a roof from the inside:
Treatment of wooden beams by injecting a special insecticide: