I once watched a movie on the network AMC (American Movie Classics)
which, from what I can remember, was about a young man who happened to
come into living arrangements in a large house owned by a female opera
singer who, reasons unknown to myself, had (I believe) five hundred
(500) daughters, all approximately twenty years old, give or take a
few. I did not catch the very beginning of the movie, and I cannot
remember the end, so I do not know why he is living in this house or
why the opera singer has so many (presumably adopted) children. This
was an older movie, because I remember there being a part featuring
what I seem to remember was technicolor, though the rest of the movie
did have some color, sort of like washed-out looking, like the old
Jimmy Stewart movies.

Additional information: All of the daughters were trying to date this
young man. One of the daughters played the trombone, and she would
play to wake the other girls up in the morning. One of the girls never
left her room - when the young man entered, it was black and white (so
obviously the rest of the picture was in color) and they danced to an
orchestra (which just happened to be in her room - the movie was a bit
fantastical at times.) The opera singer was not, I believe, married.
The bit with what seems to have been technicolor involved the young
man opening a display case of butterflies and they all flew away -
when he whistled, they entered the case again. There were not many (if
any) other men in the movie until the very end. Again, this movie was
aired on AMC between five and probably ten years ago - it was
definitely hosted by an older gentleman (you know, where they talk
about the movie in between commercials.) When the young man first saw
the five hundred young women downstairs of the case (the point of the
movie where I remember seeing from), he was startled by their
presence, leading me to believe that either he was new at the opera
singer's house (more likely, since there were five hundred of them and
only one of him) or that they weren't supposed to be there. Also, the
young man may have had amnesia, though I am not sure - I never saw the
very beginning.

I apologize for not having very much information about this movie - I
saw it probably seven years ago and it was very good, and I have tried
to remember the title of it ever since to no avail (Man of the House
comes to mind, though I have searched that and similar titles and
found nothing.)

I believe you are remembering the 1961 film "The Ladies Man," in which
Jerry Lewis plays a young man named Herbert H. Heebert who takes a job
as a handyman in a huge rooming house run by a retired opera diva
(played by Helen Traubel). Herbert soon learns that this is an
all-female rooming house occupied by a multitude of beautiful young
women. All the girls chase him, but he ends up falling for a trombone
player (Lillian Briggs). There is a scene involving butterflies flying
out of a case, as you've described. Much of the film is rather
surreal, with interesting use of color effects.

One of the most memorable things about "The Ladies Man" is the
incredible set, which resembles a multi-level cutaway dollhouse:

Jerry Lewis Comedy
http://www.jerrylewiscomedy.com/pix/asib20.jpg

If you'd like to own a copy of the film, it's available on DVD:

Amazon: The Ladies Man (1961)
http://www.amazon.com/gp/product/B0002NY8VM

I hope this is the correct movie! If it is not, please request
clarification; I'll be glad to offer further assistance before you
rate my answer.

Best regards,
pinkfreud

This was a very quick, concise answer to a problem that has been
plaguing me for several years - thanks!

Thank you very much for the five stars and the generous tip!

~pinkfreud