It's the leftovers after you melt the comb down for wax. It contains cocoons, propolis, etc. It also contains the pheromones from the hive. Great for attracting swarms.I've never heard the term "slum gum" . . .
NO, never seen any problems. In fact, in Kentucky, wax moth and small hive beetles will not bother the old brood combs if they are completely dry and been out of service for some time. Mine stay in the swarm box all year, and they never bother them.But,that still leaves the question as to whether or not anyone has seen wax moth or SHB infestations with it?