I split my first hive 2 weeks ago and have the entrance blocked with about 3 inches open. Hive is building up fast. Queen's laying well, lots eggs, larvae, capped brood, lots of orientation flights. Volume of arrivals and departures is still a fraction of the donor hive but picking up daily. I notice a few bees that don't seem like they belong, like they fly to the entrance, hover, attempt to land, hover some more, then fly off. This isn't during orientation time and I have traced one or 2 back to the other hive. How much longer should I leave the reducer in place? It's hot and I am just a bit concerned for ventilation, but I want to prevent robbing if it's still a possibility. Thanks...
How big is the hive in terms of a brood box? If it's about the size of a 3 lbs package, I wouldn't have any problem with taking the reducer off.
If I open the hive maybe 1/3 of the top bars have bees walking around on them and with the exception of the honey frames the brood frames are just about solid bees.
when the entrance become real congested then open it larger or remove it, you just have to watch robbing when a hive is not up to population.