Three years running, almost the exact same thing has happened at the exact same time of year. Four different genetic lines of honeybees. New boxes and frames for some hives.
Very few hive beetles. Veroa treatment with oxalic acid has kept mites in check. Good laying pattern from the queens. Then sometime in July-August, the queen dies.
My good stewardship and care doesn't matter if my neighbors and upstream HOA poison the place.