Blue banana squash...

I would have thought you harvest them as you would any other squash, but they are very pretty!

I grew the Jumbo pink banana last year (it turned out yellow more than pink).  I harvested one early on because I wanted to eat it!  The others I left on the plant until the leaves died back in mid autumn, as I wanted to store them and you need the skin to harden up as sunshineband says.