I just got through going through my hives. I had wood bound queen excluders on top of two of the hives. I was going to see if the queens would fill on up the lower mediums with brood...I guess I was using as a queen "includer". Anyhow, I had already read that beetles can get in the grooves that the wires are held in so I was on the look out. Yelp, there were some there...not overloaded, but more than I wanted there. The queen excluders are no longer on the hives now and I just spent about 30 minutes going around the edges of those excluders and stabbing the black slimers.
Those suckers were using those grooves like an interstate highway. The bees had been working on covering (not filling) the grooves with propolis. The shb could still travel *beneath* the layer of propolis that the bees had put in the grooves...in other words the bees weren't filling the grooves up, they were putting a layer over the top of the groove. I suppose that eventually they would have completely covered the grooved areas and trapped the beetles inside...maybe.
Anyhow...no more wood bound excluders for me!!! Lesson learned. Probably no more excluders of any kind...I made all my honey off of one hive this year, 80 pounds worth, and it had no excluder.
On a bright note...the bees are looking good.