Sorry 'bout your bees, mine are still hanging tough (1st year), but battled VM & SHB thru late summer, fall & early winter.
I had bearding so bad this summer, that I made some vent boxes that were 100% effective. I have the bottoms (left & right) closed off with PVC caps for winter as the weather dictates. This sits over a west beetle trap.
A smart man would have duplicated the bottom vent for the top, then I could have used PVC caps there as well - drilled the wrong size holes. Now I just have some slotted foam stuck in the top. My top vent also has an entrance, but I shut it down for SHB control.