Well, sigh.
We opened the green hive and found it was queenless.
No brood whatsoever.
To fix this, we decided to combine hives, using the newspaper method.
You place one sheet of newspaper on top of the hive with the queen, then poke small holes in it.
Then place the queenless hive on top of the sheet of newspaper.
The newspaper will protect the bees from being overwhelmed by the pherenomes of the new hive. It will take about a day for them to get used to them, and by that time they will have eaten through the newspaper. Boom. You have added your queenless hive to your queened one.
And, as a side note, this is the first year we have been able to grow sunflowers! 
This makes us — and the bees — very happy.
