Song for Charlotte's Daughters

Here's an idea I like: the final song will be "Song for Charlotte's Daughters, in which Wilbur first discovers, then welcomes, then pleads with, then agonizes over, and finally accepts the baby spiders and what they must do every year. The memory of Charlotte sustains him. Once the work of his song is done, Wilbur can close his eyes for a snooze on top of his manure pile. I imagine a light drawing in on him, then to black.
(In saying so, I hope I'm not stuck on the image of Porky Pig at the end of those Bugs Bunny cartoons from years ago.)
The most complex bit in the last scene is when this happens: One by one, they climb to the top of the fence, stand on their head, point their spinneret in the air and let loose a cloud of fine silk. The silk forms a balloon. Each spider lets go of the fence and rises into the air. The general effect is one of bursting, incl explosion of light and music. The air fills with tiny balloons, each carrying away a spider.
A note to myself says, Let the designer figure it out! Which keys right in to what I hope for this play: that a group of professionals will build and perform it. 
Maybe the most complex bit in the last scene is that time passes first a season at a time, then in a rush over the rest of Wilbur's days. Will be tricky to pace. It is the denouement of the piece, so things speed up toward their conclusion, but must stretch out a little, too.