The goat loves wood. But not living wood that grows out there. Among other things, the wood that is built into our houses is attacked. But this often has a supporting function. It can have devastating consequences if it loses its stability. That is why the house buck should not be ignored lightly. Some federal states have even introduced a reporting requirement for this beetle.

Hausbock or Holzbock?

The house longhorn feeds on wood. So it makes sense to give him the name Holzbock as a middle name. In fact, many people call it that. They think that is correct and unequivocal. Little do they know they are wrong. Another animal named Holzbock already exists. And it’s not a related beetle species. The wood tick is a species of tick that lives outdoors and also infects humans. What she doesn’t do is chew on the wood. It is questionable whether the paths of these two animal species often cross at all. If you’re looking for more information about the Holzbock tick, you’ve come to the wrong place. But if you mean the “wrong wooden block”, you should definitely read on.

What does the house goat look like?

The house longhorn, Latin Hylotrupes bajulus, is a species of beetle. In addition to the gnawing beetle, which is colloquially referred to as woodworm , it is the most dangerous wood pest in this country when it comes to dry wood. This longhorn beetle is easy to spot:

  • becomes up to 25 mm long
  • has an elongated, flat physique
  • is usually dark brown or black in color
  • the legs are rather lighter colored
  • on the elytra he has white patches of hair
  • the antennae are very long
  • about as long as the rest of the body

When and where can you discover it?

This species of beetle hatches in warm temperatures, which is why the animals can be seen from around July. Its natural range is coniferous forests. But it is also known to find a way into man-made buildings. The beetle only lives for three to four weeks and does not eat anything during its short lifespan. It is therefore not the actual danger for built-in wood. It is its voracious larvae that are granted a much longer life.

identify larvae

Each female longhorn beetle lays up to 1000 eggs in midsummer. Cracks and crevices in dead wood are chosen as the ideal storage location. Lumber is also deadwood and can, under certain circumstances, serve as a storage location. Larvae hatch from the eggs and spend their entire lives in the wood. Depending on the protein content of the wood, it can take three to ten years until pupation occurs. Hardly anyone will see her during this time. However, if an infested beam is sawn in half, you will see:

  • ivory colored
  • elongated body, up to 30 mm long
  • it is clearly articulated
  • more oval than round in cross-section
  • hairy but hardly visible
  • the head is slightly larger
  • has feeding tools and pinpoint eyes

Temperatures of around 30 degrees, as is the case with roof trusses, and humidity of over 40% are among their preferred living conditions.

Recognize infestation by the damage

The larvae live inside the wood, eating their way through numerous tunnels without being immediately visible from the outside. You should therefore prick up your ears if you only hear gnawing noises. Superficial bulges similar to varicose veins could also be an indication of an infestation. Only when the beetles hatch years later do visible holes appear:

  • they are oval
  • about three by seven millimeters in diameter
  • Traces of wood flour can be seen at the entrance to the hole

The house longhorn leaves the wood through these exit holes to mate. If the infestation is only discovered then, the damage done can be enormous. The wood may soon no longer be able to fulfill its supporting function. However, holes in the wood are not always a sign of an acute infestation. They can also come from earlier times.

Tip: Since the feeding holes of the larvae are often directly under the surface of the wood, you can easily detect any cavities by tapping them.

Favorite wood

The Hylotrupes bajulus prefers softwood that is not impregnated as lumber. This is usually the case with roof trusses. But furniture can also fall victim to it. Wood from deciduous trees, on the other hand, is not on its menu. Only so-called sapwood is attacked. This is the outer, young part of a tree trunk that is physiologically still active. If a piece of wood has not yet been attacked by the house longhorn, the probability of an infestation decreases as it ages.

risk of confusion

Holes in the wood do not always have to come from the Hylotrupes bajulus. These can also be, for example, disc marks or wood wasp holes, which do not pose a great danger. Surely an expert can tell the difference. He must also be consulted to assess the damage.

determination of the damage

Hardly a layman will be able to correctly assess the extent of an infestation. DIN 68800-4 for the control of animal wood pests therefore provides for the involvement of a wood expert to assess the damage. Although this part of the DIN regulation currently has no legal force, it is common practice. In your interest, too, the involvement of a specialist is advisable. After a detailed examination on site, he will determine the severity of the infestation. He also checks whether combating is possible or whether parts of the wooden structure need to be removed or replaced with new load-bearing elements.

Tip: Don’t rush, longhorn lava won’t bring down a house overnight. If necessary, you can also obtain a second expert opinion before you actually initiate expensive construction work.

obligation to report

Some federal states provide for an obligation to report an infestation by this wood pest. It is currently the federal states of Saxony and Thuringia that have legally enshrined the obligation to report for longhorned bees. But it cannot be ruled out that other federal states will follow this example at some point and decide on the obligation to register themselves. If you are dealing with an acute infestation of Hylotrupes bajulus, find out about the legal status from the responsible authorities. If you have commissioned an expert with the assessment, he will certainly be able to tell you which federal states have a reporting obligation.

Control of the wood pest

Pest control can be labor intensive and costly for wood used indoors. If fighting is still worth it. Hardly any homeowner will be able to judge which of the methods detailed below is the right one. He can only trust the recommendation of the expert. Even if the recommended measures can be very expensive, it is strongly discouraged to try to bring the situation under control by doing your own tests. The statics of a building must not be endangered, otherwise it could collapse in whole or in part.

Various control methods

  • Fumigation: Use of poisonous and suffocating gases against house longhorn and its larvae
  • Chemical treatment: Treatment of boreholes and wooden surfaces with chemical agents
  • Hot-air method: Generating overpressure creates a “hostile” temperature of over 55 °C inside the infested wood
  • Microwave method: Irradiation through locally infested wood to destroy insects dwelling therein
Note: Depending on the infestation, combating it can cost a few hundred euros to several thousand euros.


Anyone who is familiar with the dangers of this wood pest will certainly be interested in whether prevention is possible. However, treatment with chemical wood preservatives is strictly regulated by law. It is better to use wood with a high core content, as the pest prefers the soft sapwood. It also doesn’t hurt to tap accessible roof truss wood for cavities at regular intervals. In this way, action can be taken before major damage can occur.

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