I've got about a 4 year old peach, and a few blueberries.

Last year, the peaches mysteriously vanished one day, even though I
had sorta draped netting over them.

Is there an alternative, and when should I be ready for the assault?

Netting an 11' tree is no easy matter!

Also, I have some clusters of peaches, should I thin out the extras?

Jeff