Antiques are beautiful things. The discovery of an old treasure at a flea market is an imaginable situation in which even modern man can feel like a treasure hunter. Such a discovery succeeds again and again today. A closer look at the acquired antique reveals clear traces of insects that have satisfied their appetite here. Here you can find out how to recognize a woodworm infestation and how to fight the woodworms.
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identify woodworms
If you notice small holes of unclear origin when buying objects made of old wood, you should find out as much information as possible about the history of the object. Previous parking space, temporary storage in a shed, “victim” of a burst water pipe – all such details can give you a lot of clues as to which pests have in the past feasted on your new “piece of wood” or are currently still in the process of attacking the wood damage.
Live woodworms?
If it’s an old piece of furniture, there’s a very good chance that the holes you see in the wood are caused by woodworm. But these woodworm holes are almost the same as the object itself.
If a wooden item has woodworm holes resulting from a long history of woodworm infestation, the wood no longer has live woodworm or woodworm larvae. Subjecting the holes of long-gone woodworms to a treatment to combat wood pests can significantly swell the performing restorer’s account, but it still doesn’t make much sense.
It can become dangerous if the restorer or new owner also chemically combats this completely superfluous treatment. Most woodworm remedies contain neurotoxins such as permethrin. They are currently the subject of a large number of legal disputes in Germany because people with health problems are fighting back. This poison lasts particularly well and for a long time if introduced into a dead woodworm hole in dry wood. Anyone who is informed about the dangers of the chemical agents and therefore puts the secretary allegedly infected with woodworm in the shed while the woodworm is being combated will, with a little luck, cause even more mischief because it is damp in the shed and the cupboard is only really there is ruined – and it is not protected from the poisoning either. The pyrethroids adhere very well to all surfaces. They cannot be wiped away there either, but over time they become dust on the piece of furniture or in the air.
“Clean” holes are mostly history
It is not uncommon for older furniture to have holes caused by woodworm infestation. In the past, even valuable pieces of furniture were often stored in very poor conditions. Woodworms like to thrive in such cool and damp locations, but they have long since died out. At the latest when the cupboard was standing in a well-heated place for a long time. Such “historical” holes do not show any of the signs of infestation mentioned below. They are the same color as the rest of the wood and usually have an almost round, sanded edge.
These woodworm holes do not offer any reason to fight woodworm, but they can and should be closed. For this purpose, small, handy special devices are available in the restorer’s shop, with which you can seal the woodworm holes with liquid hot wax of a matching colour. The wax also strengthens the wood at the same time, which is a very useful method.
Signs of a current woodworm infestation
Before you dig deep into the poison box, you have to observe a little whether there is a woodworm on the way at all. The following signs indicate a current infestation:
- small mounds of wood flour near the holes, on the floor, or on any underlying trim
- they are caused by the predatory insects that prey on the wood destroyers
- Trick: take a new vacuum cleaner bag and vacuum out all the holes, maybe there will be wood dust in the bag afterwards
- conceivable if a piece of furniture stood damp in between and a woodworm moved into an old corridor.
- watch out for predatory enemies of the wood destroyers
If you can conclude from all these signs that someone is actually “on the move” in your wood, the next step is up.
Which worm is in the wood?
There are woodworms (which are not called that), but there are also many other wood-destroying insects. They can be roughly divided into two groups according to their habitat. Some “wood eaters” thrive on fresh wood, while others feast on wood that has already been felled, stored or used. Interesting for “woodworm fighters” are the latter, which are also divided into a whole range of species. They differ in aggressiveness and need for control:
1. When it comes to dry, mostly built-up wood with a moisture content below about 15 percent, the following serious pests could be at work:
Longicorn: with oval holes in the sapwood of softwood
- between 5 and 10 mm in size
- cylindrical droppings
- Splinter beetle: for circular holes between 0.8 and 2 mm
- originally migrated with imported hardwood
- its gnawing marks are as fine as powder and clog the holes quite tightly.
2. You will only harbor a woodworm if you are dealing with wood that has a moisture content of more than 15 (14) percent. This woodworm is actually called the “common woodworm”, eats hardwood and softwood, produces holes of 1 to 2 mm with very fine and sticky wood dust (preferably in the sapwood) and rice-like droppings.
1. The house longhorn (Hylotrupes bajulus)
is one of our most widespread and dangerous wood pests. It loves coniferous wood with a moisture content of between 18 and 30% and only stops developing when it is less than 10% dry. This makes it one of our most prominent destroyers of building timber such as roof trusses.
If a house borer infestation is found, however, one must usually assume a large-scale infestation. First of all, the entire wooden structure should be examined. Then all infested wood should be cut down to the healthy cross-section. The surface is freed from all loose parts with a wire brush. Subsequently, chemical treatment (soaking) is used against the house longhorn, preferably by a specialist company. Depending on the wood preservative, the wood may need to be watered at the same time.
2. The spruce beetle (Lyctus spp.)
is actually the only insect you should really be wary of in your living room. It is constantly being introduced to us with wood from tropical regions and can even be transferred to native deciduous trees. The sapwood beetle can sometimes multiply surprisingly quickly far from home and it only stops eating your hardwood when the moisture content of the wood reaches 7 percent. Every normal living space has at least 12 percent moisture, and so does the wood in it. It can be killed by heating or by using suitable contact insecticides or by fumigation.
3. Control common woodworm or woodworm
The woodworm or common woodworm that is so familiar to us prefers a cool and damp climate and only stops developing larvae when the wood is very dry with a moisture content of 10 to 12 percent. When it comes to combating it, chemistry is now the last priority:
Despite its name, the common scavenger beetle is actually not that mean at all, but with warmth and a little time it is quite easy to drive away without chemicals:
The first option not only works without chemicals, but also with surprisingly little effort.
- Place the infested piece of furniture in the heated living room and wait
- do not add moisture by frequently wiping the furniture or the floor
- Larvae die off on their own as the wood becomes increasingly dry
If it’s such a valuable piece that you’d rather not wait, the next option is to kill the critters with heat.
- Transport larger pieces to a specialist who offers treatment in a humidity-controlled climate chamber
- Wooden object is brought to an internal temperature of at least 55 degrees for at least 1 hour, then the worms are history
- Simply put smaller objects in your oven or in the sauna at home and heat them up
- Be careful with the humidity in the sauna
The last thing you should think about is chemical treatment. This is by no means an easy matter.
People should really not come into contact with the nerve toxin in the woodworm remedies. If you want to purchase a remedy yourself, you should be able to name the harmful organism and the severity of the infestation. When it comes to components, only qualified specialists or experts are often allowed to carry out the treatment anyway. Sometimes you also have to observe the Federal Species Protection Ordinance or bat protection regulations. Sometimes a consulting engineer or structural engineer is required. It is not uncommon for several control options to be weighed against each other. Then you should know that wood preservatives that fight each other can have an unfavorable effect on each other. Chemical control is actually almost impossible to carry out on your own.
Conclusion
If it’s really just a woodworm, you can actually be happy that “this worm is in there”, because it can be stopped quite well by heat treatment. If you don’t know “who is gnawing there”, it is definitely better to consult a specialist than to start experiments with dangerous chemicals yourself.
