Symptoms
- Droppings on the keybed, under the keys or at the bottom of the case
- Chewed or thinning felt on hammers, dampers or key bushings
- Small holes in felt, moth larvae, cocoons or webbing
- A musty or ammonia-like smell when you open the lid
- Keys that stick, click or no longer play properly
Likely causes
Mice nesting inside
The lower part of an upright is dark, quiet and full of felt and wool, which mice use as nesting material. Urine also corrodes metal parts.
Clothes moths eating felt
Moth larvae feed on the wool felt in hammers, dampers and bushings, especially in pianos that are rarely played.
Long periods unused
A piano that stays closed in a storeroom, basement or empty apartment for months is the most likely to be infested.
What you can safely check yourself
- 1Remove the bottom board or open the lid and look inside with a flashlight for droppings, nesting material and chewed felt.
- 2Check the hammers and the felt strips at the ends of the keys for holes or bare patches.
- 3Deal with the pests in the room: traps outside the piano, sealing gaps, or a pest control service.
- 4Vacuum loose debris from the bottom of the case with a soft brush attachment, wearing gloves and a mask.
- 5Play the piano regularly and open it every few months; activity discourages moths.
What not to do
- Don't put poison bait, mothballs or insecticide inside the piano or near the action; they leave residue and smells, and some damage felt and finishes.
- Don't vacuum or brush the hammers and action parts yourself; they are easy to knock out of alignment.
- Don't ignore droppings: mouse urine corrodes strings and pins and the damage keeps spreading.
Quick fixes vs. call a pro
You can usually handle it
- Looking inside with a flashlight
- Vacuuming debris from the bottom of the case
- Setting traps in the room, outside the piano
- Opening and playing the piano regularly
Call a technician
- Chewed or moth-eaten hammer or damper felt
- A nest inside the action or keyframe
- Keys that no longer play after an infestation
- Strong odor or corrosion from urine
What a technician will do
A technician removes the action and keys, cleans and sanitizes the inside of the case, and replaces chewed bushings, damper felts or hammer felt where needed. Light cleaning and a few felts usually take a few hours; heavy damage may need a workshop repair over several days. Afterwards the piano is regulated and tuned.
A piano holds about 18–20 tonnes of string tension. If a fix means opening the action, turning tuning pins or working near the strings, leave it to a technician.
In Israel
We often find mice and moths in pianos kept in storerooms, basements or ground-floor apartments, and in pianos left in an empty apartment during a move or renovation. The warm Israeli climate means moths can stay active for much of the year.