This is something that I've been meaning to address for several months.

I've noticed from time to time that someone will buy a piano and
take it immediately into their home.  Usually this is not a problem.
However, it has become a practice with me that whenever I bring a
piano onto the premises or into my shop for the first time there is a
procedure that I go through, because I had a problem once a number of
years ago with little living things inside an old piano.  I now follow
this routine with each piano.

The piano is placed either on a porch or space entirely separate from
all other materials.  It is then covered entirely with plastic right
down to the floor.  Then I discharge at least one can-full of insecticide
through a small opening in the plastic.  Of course the knee board and
front of the piano have been removed and set behind the piano so that
the upper and lower actions are exposed to the insecticide.

Following that I tape shut the small hole and leave the piano for
several days to allow plenty of time for any vermin that may have been
residing in the piano to be killed.  If there is any even remote
thought that the piano may be infected, I repeat the procedure a second
time so the entire process may take up to a week.

There are things inside a piano that some species regard as food.  Some
of these little critters may decide that there are other goodies around
the house or shop if precautions aren't taken.

I've been doing this for more than thirty five years since the one
problem I had and have never had a repeat of that problem.

Hal Davis