The cocoons that remain in the cell after the bees hatch are the major problem. The cocoons are extremely sticky and, try as they might, the bees cannot strip it all from the comb. Some say the darkness is caused by the feces that remains in the bottom of the cocoons. Although this may be partially true, based on what I’ve read, the bees manage to remove most—if not all—of the feces as they prepare the cell for the next generation.

What is more likely is that the sticky cocoons attract all sorts of hive debris, from dirt tracked in on bee feet (many bees times six), pollen grains, and atmospheric dust. In addition, the bees polish the insides of these cells with propolis to make the surface smooth and to take advantage of the many antimicrobial agents found in the propolis.

The color found in the dirt and debris, combined with the layers of propolis—which is usually dark—probably accounts for most of the color change.

But, you say, the inside of honey cells are brushed with propolis too. That is true, but the honey cells do not contain cocoons and they are emptied and polished seldom—usually only once a year. Brood cells, on the other hand, may be polished and reused every 21 or 22 days during the spring and summer—a huge difference.

Another difference between honey comb and brood comb is the amount of bee activity. Once a honey cell is filled the bees move on to another. But once an egg is laid in a brood cell, the uncapped larvae is fed a thousand times a day—quite a different traffic pattern.

The buildup of cocoons and propolis in brood cells is significant. Some researchers have analyzed brood comb and found that the cells become measurably smaller as the walls become thicker. If you render your own beeswax, you know how much more debris is filtered from melted brood comb than melted honey comb. Clumps of this debris, appropriately called “slumgum,” clog strainers and mesh bags, and tiny bits of it darken the liquid wax.

The question always arises whether dark comb is harmful to bees. In truth, bees love dark comb and it is often used in bait hives to attract wild swarms. I’ve heard rumors about beekeepers using black comb for twenty-five years with no ill effects.

Recently, however, there is concern about pesticide build-up in old combs, as well as the accumulation of some pathogens. Many sources now recommend rotating old black comb out of the hive every four or five years, not because of its color but to protect the hive from these pesticides and pathogens.

Rusty
HoneyBeeSuite

The upper part of the comb has never been used for brood and remains light. The lower portion has contained brood and is starting to darken. Flickr photo by Jordan Schwartz.

Depending on their genetics, bees either place the capping wax directly on the surface of the honey, or they may leave a little air pocket between the surface of the honey and the wax. These two methods make no difference in the flavor, color, or quality of the honey, but they make the finished combs look dramatically different.

The honeycomb with the air pockets is said to have dry cappings. The comb appears white or very light tan. Honeycomb with wet cappings is not actually wet, but it looks like it might be. The appearance is darker and may have a variegated pattern due to scattered mini air pockets, which have a lighter color.

While some honey bees produce both types of capping, some consistently build one kind or the other. Italian honey bees (Apis mellifera ligustica) are known for producing white, dry caps. At the other end of the spectrum, Causasian bees (Apis caucasica) produced wet caps almost exclusively.

Producers of comb honey have found that consumers prefer dry cappings. Especially back in the heyday of comb honey production, beekeepers found they could get better prices for light-colored, clean looking combs. The desire for white combs is one of the reasons that Italian bees became so popular in the United States.

The practice of producing chunk honey, which is just a piece of honeycomb submerged in extracted honey, was one way in which beekeepers could sell their wet-capped honey.

Rusty

These combs came from the same super. One has dry cappings, one has wet.

If you were to cut a comb in half so you could see both sides at once, you would see the cells come together in a V shape. The angle is very subtle, so if you just glance at a comb quickly, you might miss this important structural feature.

When nectar is first placed in the comb it is about the consistency of water. Without sloping cells, the nectar would run out before the bees had a chance to dry it down.

Several years ago I put comb in a hive upside down to see what the bees would do. For many days, they did nothing. But eventually they took it apart and used the beeswax to build new comb elsewhere in the hive. Then they built a properly oriented comb where the upside down one had been. You just can’t trick a honey bee.

Rusty