I am in the process of trapping some bees out of a hollow tree. This is going on the 4th week. I put 1 frame of brood with some eggs in a nuc box near mouth of wire cone that I had installed over the hole in the tree. All is going very well, they have drawn nearly 4 frames out(just had foundation to put in the nuc box). I am going to move them into a full size box this weekend since I have a division board feeder in the nuc. I put a queen in the box 2 weeks ago(removed queen cells or I believe I removed them all), she was accepted and out by the third day, went back a couple of days later and checked all was still well. Went back to the hive yesterday and BAM a different queen in the box. So I am curious as to where ya'll think she came from?
1. I missed a queen cell? Maybe, but wouldn't think they would have accepted the queen I put in.
2. She came out of the tree? Really don't have a clue about that, this is my first time to try the tree trapping deal, but I wouldn't think she would leave the old hive this soon if at all.
3. Other ideas?

Marty