Dead bees by the hundreds

Opened up the queen castle I made from the swarm to see what was going on inside. Outside the bees are 3 deep in a massive pile and more coming, all dead or dying.  I opened the hive and found no evidence there is an active queen.  They are making comb and filling with honey, no pollen and no brood or eggs anywhere.  Sent samples off to the bee lab in MD, they take forever.  Ordered some menthol on the net and have to wait for it to arrive.  This is for Tracheal mites but they are only suppose to attach to young pupae but this is a swarm with no young????  I have no idea whats going on and the web is useless on this issue.  May have to call Cornell.  Later