To save our honour, pests are only there because we are harmed at the piano or our health and do not want this. Seen in this light, we humans are also - and probably the biggest - pests for others.
Essentially, four types of pest infestation are critical for a piano, woodworms, moths, mice and mold bacteria. The latter are not only critical for the piano, but above all for its own health.
In the piano, the materials (felt, wood, etc.) and the environment (protected and poorly ventilated) provide ideal conditions for these pests. The mould bacteria ('white mould') benefit from the higher humidity required for the piano, the often inadequate ventilation and the location close to sometimes external walls. The fungal spores are toxic to us humans and must be professionally removed.
Even today in the best and most well-kept households, these pests still travel unnoticed in the instrument. In principle, an unplayed piano is more likely to be infested by pests than one that has been played. Stored pianos are particularly at risk. Modern building materials in newer pianos are already pre-treated against pests - but even this does not always provide protection.
The title photo shows a bad example for the instrument as well as for the owner and the mice. A nest of mice with two dead animals inside. But before that the animals have left considerable damage to the mechanism felts, keyboard and keyboard bottom woods. The urine of the mice also causes great damage to the instrument. It is therefore worthwhile - if there is no eager cat in the house - to take other suitable measures against the rodents to preserve the value of the instrument. Old pianos usually have lattice guards on the back and sometimes also in the pedal area to keep the rodents away. However, the mice will always find a way.
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