>I checked my hive today and there were hundreds of bees on the outside wall
>near the entrance. The frames are relatively full in the main chamber with
>lots of brood, but the beens seem to refuse to go through the queen
>excluder to the honey super.

This can be a simple case of no nectar flow and warm weather. If the brood
chamber is congested you have a greater chance of swarming. You can add a
second brood chamber to reduce the chances of swarming.

Without a need the bees will be reluctant to move away from the brood and
queen into a super. If there is no flow on they will tend to not want to
move up. If there is only foundation in the honey supers it will take a
strong flow to get them to draw it out into comb.

As for the mites seeing one just does not indicate a need for treatment,
yet. I would suggest that you test for mite populations using the "sugar
roll" method or sticky board.