As architects and builders well know, constructing a home requires careful measuring and planning. Now new findings suggest that hornets are similarly fastidious. According to a report in the current issue of the journal Nature, each hexagonal brood-rearing cell of the oriental hornet's nest comb contains a tiny crystal at its center. The resulting network of crystals, researchers say, may serve the same purpose as a surveyor's level, helping the insects maintain symmetry and balance when building their precisely oriented and uniform nests.
The construction of the combs happens in stages, starting with the roof. Observations of this process, made by Ietse Stokroos of the University of Groningen and colleagues, revealed that the hornets use their saliva to attach a crystal some 100 micrometers in diameter to the center of that roof in each comb cell. (Hornet larvae are later attached to a side wall once the entire comb is completed.) Chemical analyses of these keystone-like crystals revealed titanium, iron, oxygen and carbon, as well as trace amounts of manganese. The team assumes that the hornets collect the crystals from the local environment. But considering the fact that elements contained in the crystals are also found in the hornets' bodies, the researchers note that the insects may produce the crystals themselves.