Slumgum is a beekeeper’s term for the stuff that is leftover after rendering beeswax. While wax from cappings and honeycombs is fairly pure, wax from brood combs contains a wide assortment of stuff which may include cocoons from both bees and wax moths, excrement from bee larvae, mites, pollen, propolis, and bee parts.
After the comb has melted, the slumgum—which is heavier than wax—sinks to the bottom of the container. The majority of wax can be poured off the top and the remainder can be filtered through sieves or cheesecloth. The slumgum is dark brown to black with a unique odor that is not altogether pleasant. It also looks sort of gross.
Regardless of its appearance, slumgum is very attractive to bees especially when it is warm and aromatic. Consequently, some people smear it on the insides of bait hives to attract wild swarms. If you have some leftover, you can also use it as a soil amendment. The slumgum is broken down by soil organisms and the nutrients are then available for uptake by plant roots. And who knows, some of those nutrients probably make it into the plant’s nectar and pollen for the ultimate in recycling. What a system.