new split swarmed on me

[rookie2531]

So I grafted Easter and saw eggs May 8th. Had them in a 5 frame nuc with 5 frame medium up top for stores because they started with only 2 frames of bees and maybe after I saw she made it back from mating, i probably added a frame of brood from a strong hive approximately a week ago.after inspection yesterday, there was 3 capped and 3 almost capped swarm cells. Some open larvae, not many and no eggs. She is gone. But what really puzzling is, there was still room and nuclear wasn't even half the size I've seen from others, that haven't even made cells yet. The top medium wasn't even covered at all.

[OldMech]

Nucleus Hive     

   How much syrup do they have in the cells?  They can swarm for many reasons, one of them being because the queen has no place to lay.. if they have pollen and nectar plugging up the brood area they will swarm. 
   If you have three drawn combs, and the bees have those combs filled.... then they are plugged up and she has no place to lay.. even if you have new foundation in the other empty slots..
   Dropping in a drawn comb changes everything!

[rookie2531]

Nuclear,spell finish to blame.

I was leaning to that idea oldmech. I was thinking/hoping, they would use the syrup to draw more comb off that foundation. I pulled all syrup off them, but it might be too late. The poplar flow is still going strong. Ill definitely have to keep a close eye on them all now. I guess the good news is, they should be some big healthy queens.