Here in Lynchburg most of the drones in your hives should have been dead by now. Yesterday I did a top to bottom inspection on my 3 hives and saw one drone. I would guess and say either spray or the strong hive went on a honey robbing mission on your second hive. I had one hive, little aggressive by nature, that tried to rob another one of my hives and there where dead bees covering the ground at the base of the second hive's entrance.