I've only seen a few beetles in my three hives, but living here in south Alabama I *know* more are coming. I know that many folks recommend migratory type covers to take away a hiding place for the beetles and it makes good sense to me. It is kind of strange, though, that most of the beetles that I have seen have been on the bottom of the inner covers along with bees. I've seen these bees "chase, tackle, and pile on" these beetles so I know the bees are watching them and not just complacent with them. I've seen fewer beetles on top of the inner covers.
Currently I'm using telescoping covers, but having just a few hives I've got enough migratory covers prepared in case the beetles begin to take advantage of the inner cover space.
I keep #8 mesh wire over the porter escape hole in the inner cover (mason jar feeders) and I've see beetles between the mesh and the wood...they appear to prefer traveling through the small gap between the flat surfaces of the wood/mesh rather than going through the holes in the mesh...when you see them there it's an easy kill. :evil: :-D
Being as the beetles seem to prefer that little gap rather than going through the mesh it seems that the opening in the mesh is *almost* small enough to keep the beetles out of the hive. I've toyed with the idea of using spray paint to lightly paint the mesh on my screened bottom boards and the screen over the vents...this would effectively tighten up the mesh openings a small amount and maybe prevent the beetles from entering via either point. A warning here, though...I've found only one spray paint that is reported to actually work on galvanized metal...Krylon H2O latex...it doesn't say it's for galvanized but as for as that goes their alkyd paints don't have a warning on them saying *not* to use them on galvanized metal, either. The article I read stated that they don't think Krylon knows this paint will work on galvanzied. Naturally you could use a paint brush but I don't think it'd give quiet the effect that we would be looking for. Don't use the Krylon latex primer, either, being as it's alkyd based, too. Just a newbee thought....