Blame it on your dad. He'll feel so guilty, that he will go and pick them up for you!
Seriously, I think you should get someone who is comfortable with walking around on rafters to go through and pick up as many as they can find. The one you miss will dissapate eventually, but it will smell a hell of a lot less that if you leave them all. Sorry, there is no magical answer other than the obvious. PICK EM UP!!!