Hi,  When we were in UK we had (and still have) a Racca Piano Melodico
which had woodworm infestation when we purchased it.  Upon the advice
of a professional museum conservator we contacted Rentokil, UK's
leading woodworm exterminators, regarding their fumigation process.
They had delivered to us a 20-foot-long steel container (as used on
trucks, railways, etc.) into which we placed the Racca and every other
moveable mechanical instrument, furniture, etc., that we were in any
way suspicious of.

The Rentokil operatives turned up, sealed all the gaps in the container
with duct tape and filled it with gas (don't know what they used, but
they said it was shortly to be banned by EEC regulations!) and it
remained thus for a week.  At the end it was released and we removed
the instruments again.

Six months later the Racca piano started exhibiting the odd hole here
and there again.  We contacted Rentokil again, who said that the
treatment is not infallible, and that occasionally a re-infestation can
occur.  We repeated the entire operation, in the hope that the second
application would do the trick.

The piano remained hole free for a while, but is again producing woodworm
holes...  We squirt it from time to time with proprietary woodworm fluid.

The ultimate answer appears to be to burn it!

David Evans
Director, Revelstoke Nickelodeon Museum
http://www.revelstokenickelodeon.com/