I am new to beekeeping, having installed two new hives in April 2014. One of the hives was doing great and the other so so. I live in NC and on recent hot days many of the bees would hang out on the front of the hive...I mean a lot of them. this was after I added a super 3 1/2 weeks ago. I noticed about a week ago that they had just about filled up that super. Anyway, late last week I noticed that they were no longer hanging out on the front of the hive and it appeared to be less active. Went into the hive this past Sunday and noticed that clearly many of the bees were gone. Could it have been from overcrowding? Should I have added another super sooner? I noticed only one queen cell, but don't they normally make more queen cells when raising a new queen? There was plenty of capped brood so I am hoping a new queen will be raised and the numbers will grow. Thanks for any insight!