i did see one where the bees had managed to about half cover it- but I told the guy to get rid of it and just put in a solid board. I also told him not to risk the bamboo queen excluder though it looked half decent.
I have been using a few quilt boxes with fly screen mesh and a thick layer of wood chips. On some iof them the bees have half propolised the mesh. However they seem to have been happy to leave some airflow.
Also my friend Vicky in sydney is using propolis mats on some hives and the bees are filling them up.
On a couple of occasions people put mesh over the hole in flow crown boards. On both occasions the bees propolized the mesh while leaving a perfect circle the size of a 20c piece in the middle. This was after one bloke found a heap of drones in the roof as he took it off. He thought they were bees which must have startled him a bit. He didn’t want that to happen again, so he blocked the hole with mesh which kind of went against him because his colony swarmed sooner rather than later. It didn’t matter because they would have swarmed anyway. I previously advised him to leave the hole open while lifting the roof once a fortnight to check on the population growth. That way I could have split the colony once the roof started to get populated, to try to prevent swarming… Needless to say, he took no notice.
In reply to my comment on the 11th of March (5 weeks ago), the honey supers are gone, yeah!!!. Because we had a lot of rain during the past 5 weeks, I cautioned him about putting the supers on too soon. He was determined he was going to put them on, regardless of the status of the colonies.
This morning he had to pick up a colony for his son’s genuine flow hive. He said “I think I put the supers on too soon”. He was in a hurry & couldn’t talk long, his son lives about 2 hours away.