In natural comb building, bees build for the immediate present, with no evidence of a plan for the needs of the future.
When first built, combs are light yellow or almost white in color, but after brood is reared in the cells the comb is darkened by the “cocoons” left by the brood.
The color varies with the sources of honey and pollen at the time the comb is being built.
It is also known that waxes vary similarly in certain physical properties.
These so-called cocoons consist of larval skins and excreta, with the possible addition of a portion of the delicate silken cocoon.
These deposits increase with successive rearings of brood until the bases of the cells are appreciably thickened while the outer parts of the side walls remain practically unmodified in size.
If an old comb is soaked in water the layers of deposits may be readily separated.
The combs are also darkened by deposits of propolis on the cappings of honey cells and the tops of combs are often strengthened by deposits of this substance, especially when the combs are attached to rough wood, as in a hollow log.
Excerpted and edited from:
Beekeeping; a discussion of the life of the honeybee … 1915. Phillips, Everett Franklin, 1878-1951.