Bob, sorry I don't get on here very much, but the reason I quit using the pan in the TB hive, I have no proof but I think a man with ATT was going to run a telephone line close to my hives, this one was the closest and was sprayed all bees were dead in hive or on ground next to hive. the next year a swarm moved in and within 2 days they were dead also. I did away with the hive. Like Jim said I never had trouble with the bees messing with the hardware cloth, # 8. If I got a real bad case of shb's I have in the past put a CD case or 2 in the hive. put some butter flavored Crisco in the center, get some combat roach poison, it comes in a syringe, phimpronil probably spelled wrong. been a long time since I used it, but can help if they get bad. You put a small line of it around the dab of Crisco. The shbs love the Crisco will get in go through the roach poison and will die. I did put a few extra holes in the side of the case with a hot ice pick. not big enough for a bee. I just done this if had lots of shbs, until they were manageable.
Good luck to you and your bees,
Joe D