deedee, if you've used a bleach solution on the inside of the nestbox then it is important to let the box air dry before closing it back up. I only do the bleaching at the end of nesting season and if there's been an unexplained loss of a nestling or adult bird that could be attributed to disease. Otherwise, my nestboxes get a good brushing out and a renewed application of vaseline on the inside of the roof to protect against wasp nests and then are ready for the next round.
I think your papa blue will figure things out.
Kathy

thank you for your advise, their nest box was pretty awful we had a lot of rains here in the St. Louis area....but I used a little bleach with dawn and rinsed real well I did let it air dry for a day and it was almost 90 Sunday. He's not gone back in he just flys up to the hole and looks in then sits on top of the box then back to look in the whole again. I've never heard about the vaseline I'll put some on even though I haven't seen any wasp better to be safe than sorry.

As long as you rinsed well the box should be fine. Be careful mixing cleaners, though, both for yourself and for the blues. As for the vaseline, I apply a thin coat to the ceiling and around the sides about an inch down, then buff with a paper towel until the surface just has a sheen. Some folks use wax or bar soap, but this is easier to apply, in my opinion. Good luck and keep us posted.
Kathy