Two days ago I opened up a very healthy hive (two deep brood chambers and lots of bees) and inserted an Apiguard tray inbetween the chambers to treat for varroa mite. At the same time, I installed a varroa mite screen between my bottom board and the bottom hive. I have another hive across the yard (about 40 feet away) in which I also put an Apiguard tray, but was unable to install the varroa screen since the hive body was attached to the bottom board.
The next day (and today too), the entire first hive I mentioned has been completely covered on all sides with bees, some of which are fighting with each other, as in honey-robbing. The hive wasn't open to the air that long, but the varroa screen insert did result in a somewhat larger hive opening. Also, yesterday and today were REALLY hot here in San Luis Obispo, so I know that usually results in a lot of outside bees, but not like this. The second hive, without the varroa screen, seems perfectly fine, although it was not so crowded as the first.
Has anyone experienced such behavior after insertion of Apiguard and/or a varroa screen? I just want to make sure I didn't screw up a perfectly good hive by trying to do something helpful.
Many thanks, Kathy O'Brien