Mike and I had a real queen problem.  We were constantly having to requeen this summer because they left after being placed in hive, one got beheaded, and some just didn't come back from their maiden flight.  As a result, when we finally had all colonies requeened and enough numbers, we did an alcohol mite check.  The result was five or less mites per colony in our test.  Some had zero.  The one with five was the only one of our six colonies that didn't have a queen problem.  This seemed to be a rather difficult way to have a brood break ;)  Will be doing another in mid September.  By the way, we still have two colonies with queen problems.  One we think swarmed, the other just disappeared.