We have been keeping a backyard beehive for over 25 years. While most survive over winter , the last two years were bad. One year frigid temps and they died in March with not enough bees to heat the hive. Last year they were alive in November and died in Dec of what we don't know .

So new bees arrived Monday from Kentucky. It was 80 yesterday and they were out and about. My question is my husband has an entrance excluder on and I think if should come off as they crowd thru on small opening. He says it's to prevent robber bees and keeps the hive safe. Who's right and when does the excluder strip come off?