Woodworm: Detect, fight and prevent

These tips will get rid of woodworm for sure. Everything about the wood pest and fighting it with the right means can be found here.

There's the worm in there! We cannot say with certainty whether the saying really refers to the woodworm, but we have all sorts of useful tips about the wood pest. The woodworm, which is actually a beetle larva, feels particularly at home in damp wood. There, the pest can survive in the wood for many years and eat its way deeper and deeper into its favorite food. To prevent this from happening in the first place, a few important points must be observed, which we summarize for you below in the article. If it is already too late and the worm is already in the wood, then we have two very effective ways for you to finally get rid of the woodworm. However, when fighting woodworm, you must always bear in mind that the wooden object must also be able to withstand the appropriate means. In the case of very high-quality furniture or wooden instruments, the advice of a specialist should always be consulted.

Woodworm: profile and characteristics

The woodworm is actually the larva of the common or common woodworm (Anobium punctatum). The adult beetle is 2.5 to 5 millimeters long and slightly hairy. What is much more striking, however, is that his head is completely hidden by his pronotum. Because the common woodworm beetle can fly, it can also spread relatively well. However, the wood in which the adult woodworm beetle has already lived as a larva is most likely to be attacked. Incidentally, the beetles do not cause any damage to the wood, they are only looking for a copulation partner in order to be able to lay their eggs in a favorable place. A little later, the woodworms hatch from the 0.5 mm large eggs, which then pose the real problem. The larvae, which are reminiscent of grubs, quickly work their way into the wood and during their time in the wood develop through several larval stages to the adult beetle. Depending on how good the conditions are for the woodworm, full development can take as little as a year or even up to eight years.

However, the woodworm does not just blindly bore into the wood and eat any part. Woodworms are real gourmets: Although they also infest hardwood, a woodworm usually only bores through soft wood regions almost without exception. Because of this, the heartwood is often spared, while the softer sapwood tends to be eaten away. In addition, the woodworm differentiates between early wood and late wood. As can be seen in the picture below, early and late wood are nothing more than the annual rings of a tree. The light early wood is formed in spring and due to the rapid growth in this season, the early wood is softer overall than the late wood. It is precisely for this reason that the woodworm also prefers the easier to chew early wood.

Detect woodworm infestation

The woodworm belongs to the dry wood pests and therefore affects all types of built-in wood. He completely avoids fresh wood. Almost any wood can be attacked by the wood pest, which is why roof trusses, wooden windows, furniture of all kinds and other wooden utensils are potential food for the unwelcome worm represent. An infestation is also quickly detected if potentially endangered wooden objects are regularly checked for small holes. The holes of a woodworm always have a diameter of 1 to 2 mm and, depending on the severity of the infestation, they only appear sporadically. However, it is also possible for the little beasts to completely pierce a wooden object in the truest sense of the word. These holes are then a really sure sign of wood damage caused by woodworm. At this moment, however, it is not yet clear whether a woodworm is still up to mischief in the wooden hole or whether the hole is already deserted.

First, the ground directly under the hole should be checked for wood flour, as this is regularly carried out of the wood cavity by a woodworm. If wood flour is found, you should place a piece of paper directly under the hole. Now wait a few days and check the leaf for wood dust that has been ejected again (a little tip: the wood dust is best seen on black paper). However, you will have to wait a few days, as a woodworm does not eat continuously and therefore does not throw out wood flour every day. If the paper test is positive, you know that your wooden object has been infested with woodworm. Wood pests (such as woodworm) should always be combated, because pieces of furniture can even be destroyed to such an extent that, for example, a chair leg is no longer stable and breaks off.

In addition to the paper test, you should also be able to perceive the woodworm through its chewing noises. In absolute silence, you can supposedly hear the insects working their way through the wood with their chewing tools. However, we cannot confirm whether this is true.

Prevent woodworm

There are a variety of ways and means to prevent the wood-damaging worm from getting into your beloved furniture and wooden structures in the first place. Some of these are very easy to implement – ​​while others are very expensive.

The best way to protect wooden furniture and objects is to heat them. Because the woodworm can only survive in wood with a residual moisture content of more than 10%. In a continuously heated room, the wood is usually so dry that woodworm cannot infest even untreated wood. On the other hand, woods in cool places such as cellars, attics, churches, empty buildings and in sheds are susceptible. So we can summarize that all outdoor wooden objects that are stored in a cool place can also be attacked by a woodworm.

To ensure that the wood is still protected under these adverse conditions, a few basic rules should be followed:

• Wood should never lie directly on the ground outdoors
• Protect wood from moisture with a waterproof varnish
• Special preparations against woodworm infestation also have a preventive effect (“woodworm death“)

It is not always necessary to buy expensive and often toxic stains specifically against woodworm. A glaze is often sufficient to protect the wood from penetrating moisture. Chemical preparations can only be used in the case of stubborn problems. Under the names "Holzwurmtod" and "Holzwurm-Ex" glazes are sold that protect the wood preventively and prevent woodworm infestation. However, the funds are very questionable for the environment in almost every respect.

Fight woodworm

In principle, the woodworm can be fought quite well. The wooden object to be treated is often the problem. For example, a stationary roof beam is much more difficult to handle than a chair leg or other small, moveable piece of furniture. There are countless remedies on the Internet, especially home remedies, which are said to be good for fighting woodworm. Household remedies such as ammonia solution, spirit and petroleum kill the woodworm, but the odor nuisance is sometimes significant and residues almost always remain in the wood. As a result, the treated piece of furniture can still smell unpleasantly for a long time after the treatment. We therefore present two methods that work well and are as gentle as possible on the wood.

Combat woodworm with the heat method

Professional furniture restorers also swear by this control method. First you have to know that the woodworm dies at 55 °C. This temperature is usually harmless for wood, paint and the like. To combat woodworm using the heat method, the affected piece of wood must be mobile. Very small wooden furniture can be treated in the oven at 55 °C for 3 hours. This kills all larvae in the wood. Larger items can theoretically be treated in a sauna, but who has? In summer you can use the strong sunlight to reach the necessary temperatures to fight woodworm. On a sunny and warm (preferably hot) day, you can place the item in the sun under a black foil as airtight as possible. Below that, it can quickly get warmer than 50 °C, which is why the temperature profile should be monitored with a thermometer. Here, too, 3 hours at 55 °C are sufficient to kill the woodworms. Only when the wood is thicker than 6 cm does the treatment need to be extended. If there is not enough sun, the item can also be stowed in the car or in the greenhouse. It definitely gets warm enough there in the blazing sun! Woodworm can be combated very gently and effectively with this method.

Important: The treated wood must cool down slowly (preferably overnight) under the foil. If you took the warm wood directly out of the foil, stress cracks could occur. The same applies to the oven and sauna.

Fight woodworm with the alcohol method

Only pure isopropanol alcohol should be used for this control method. This alcohol is characterized by the fact that it evaporates completely without leaving any residue and is also very cheap at around 5 euros per liter. This method is more suitable for small wooden objects, since too much isopropanol evaporates at once with larger wooden objects. This can result in a highly explosive isopropanol-air mixture, which would immediately explode if exposed to an ignition source. For this reason isopropanol should generally only be used in well-ventilated rooms! However, if the work is carried out outdoors, there are no problems with the evaporated isopropanol. The wood to be treated will survive the alcohol treatment unscathed, however certain varnishes and wood treatments can be attacked by alcohol. Therefore, find out beforehand whether your treated wood surface tolerates isopropanol or test it on a small area.

Once everything has been clarified, the work can begin: Thoroughly brush the wooden object with the alcohol. You should apply as much isopropanol as possible, especially in the area of ​​​​the wood holes. When applying, proceed as quickly as possible so that as little alcohol as possible evaporates. After application, the wooden object is thoroughly wrapped in painter's film so that the isopropanol can penetrate the wood and does not evaporate. After an exposure time of three days, all woodworms are also fought here. If the wood is more than 3 cm thick, the alcohol may not be able to penetrate the core of the wood and the treatment may not fight all woodworm. For thin wood, however, it is often a very good method to completely combat woodworm.

The following products have proven themselves with us:

• isopropanol: Particularly suitable for combating woodworm in smaller pieces or areas of wood. Use only in well-ventilated rooms.
• woodworm death: Water-based biocidal product for targeted insect control. Fast and permanently effective, compatible with wood care products.
• woodworm spray: Mono-active preparation as a water-based solution ready for spraying. Reliably combats woodworms, house longhorns, their larvae and wood-damaging insects and prevents re-infestation.

Woodworm infestation on load-bearing wooden objects

It becomes less fun when important wooden elements are eaten by the woodworm. A massive infestation by the woodworm can seriously damage load-bearing wooden components. This often only happens if the roof is leaking and water can therefore penetrate the wood. In any case, you should seek the advice of specialists. Trained pest controllers can correctly assess the severity of the infestation and have special control methods to get rid of the woodworm. Because a thick roof beam cannot usually be treated satisfactorily with the two control methods presented above. For example, the professionals can direct a gas into the roof beams so that the woodworms can be fought quickly. However, such agents are not safe to use and therefore they should only be used by professionals to combat woodworm.

The larvae of the woodworm are strongly reminiscent of grubs. In our special article we explain how you can recognize and combat them.