Really need some help with this one. My friend was checking his hive the other day when he noticed what looked like someone had taken a drill and bit and drilled a hole dead center of previously capped brood cells. You know how when you drill and withdraw the bit it brings some of the material out with it. It looked just like that and a perfectly round hole. It happened to about 10 to 15 cells in the middle of a patch of brood maybe 4 inches in diameter. What could have caused this? The cells were not discolored at all, everything else looked normal. Thanks for your help.