In the case of honeybees, just before pupation, the larvae cover the waxen walls of their cells with silk (Huber 1814; Arnhart 1906), paying out the fibres randomly so that, by the end of the spinning, the walls are covered by thin sheets of silk proteins are released from the secretory cells as a homogeneous substance that polymerizes in the lumen to form compact birefringent tactoids. 

After spinning the larvae smear, a small amount of material from the Malpighian tubules onto the hardened silk layers and faeces are also excreted between silk layers (Jay 1964). Subsequently the larvae produce a colourless pollen-free substance and then a yellow pollen- bearing one (from the anus), both of which are applied in turn to the silk base (Verlich 1930; Jay 1964). Nothing further is known of these four substances, but they invite the analogy of a sizing in paper manufacture, which is the incorporation of other material, in particular papers to act as a protecting glaze by changing the physical characteristic of the material (paper/wax).

Successive generations of brood apply more silk to the walls, the cells become smaller and the mass ratio of silk to wax greater (Chauvin 1962). Thus, old brood combs are heavily impregnated with silk (Figure 2) which is inseparable from the wax except by chemical and/or heat treatments. The development and maturation of brood comb proceeds from a single-phase material, pure white wax, to a coloured fibre-reinforced two-phase composite

Hepburn, H. R., Duangphakdee, O., & Pirk, C. W. Physical properties of honeybee silk: a review. Apidologie, 1-11.

* * *

Varroa destructor preferentially invades larger honey bee brood cells. Consequently, it was
expected that brood in old combs with reduced-size cells would be less infested than the brood in new comb
cells. An old brood comb was placed in each of eight Africanized honey bee colonies, along with a new,
naturally constructed comb (without comb foundation). The mean percentage of brood cells infested with
V. destructor was significantly higher in the old combs (22.6%), than in the new combs (9.75%), even
though the inside width of the cells was significantly smaller in the old (4.58 mm) than in the new combs
(4.85 mm). Within the range where there was an overlap in the width of brood cells between old and new
combs, which was from 4.5 to 4.9 mm, the old comb cells were over four times more frequently infested
with mites than were the new comb cells. Some factor other than cell size makes old brood comb cells much
more attractive to V. destructor than newly constructed brood comb.

Piccirillo, G. A., & De Jong, D. (2004). Old honey bee brood combs are more infested by the mite Varroa destructor than are new brood combs. Apidologie,35(4), 359-364.
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