A healthy, overwintered colony of midnight (hybrid) bees swarmed on April 6th and 9th. A careful inspection on the 9th revealed several empty queen cells, a couple maturing queen cells, and some capped brood. An inspection today (April 23rd) yielded no brood in any stages of development and all queen cells empty. Has this colony become queenless or is there still time for a virgin to mate and lay? Do I need to introduce a young, mated queen to this colony? Or do I just need patience? Help, please.