Where had they gone? Why were only some of them missing? Was there some sort of blogger glitch? Was this the work of a nefarious product picture thief?
After a little light detective work on my part I came to the root of the problem. If you delete a photo in your g+ account it gets deleted from blogger as well- even if it was a separate upload!
So all of those nifty pictures I had up? Gone.
Unfortunately I did this after deleting files on my computer so I don't have any extra copies or any way to get them back. There's nothing left to do but call it a learning experience and move on.
Tomorrow's a new day.