I knew it was coming because it climbed to the top of the Bug Bottle and was hanging from the lid in the 'j' formation.
Apparently the sex of the butterfly-to-be can be determined at this stage by looking at the cremaster, the structure from which the pupa hangs. This is the best I could do in a hurry with my camera but I venture to say that it will be a male.
I'll have to look closer with a magnifying glass to be sure.
We will be releasing our last butterfly in about 10 days.