I check my apiary everyday just by walking near it. I walked out a saw thousands bees dying. Littering the ground. I have seen this last year August 30th. My hive found another hive sprayed by insecticide. They are robbing the free honey. The bees come back and recruit more bees. They pass the honey between themselves. Then the whole hive will crash and die.
I pulled the super off the hive and closed the entrance and hosed off the cement. I use screen bottom boards. They have ventilation. Last year it helped I only lost good portion of the hive along with the queen. I amazes me what the general public don't understand. To give an update, the next morning I opened the entrance. Then open the hive to clean the screened bottom board from all the dead bees. I watched for the rest of the day and I see some foragers and no more dying bees. I will go back into the hive in about a week to see if there is a queen. I'm expecting not. The hive lost about 1/8th of the amount of bees. 02/17/2017 I checked the hive this afternoon.I saw eggs and the queen. She made it. The hive is expanding.