Scaling properties of honeycomb across bees and wasps

The regular cells of honeycomb have fascinated scholars and mathematicians for millennia, yet research continues to produce new insights into the evolution and structural properties of hexagonal nests. Humans use hexagons in construction to provide strength while using minimal material, and bees and wasps have evolved hexagonal nests for the same reason. It is not just the hexagonal cell that provides structural properties to these nests, but also individual cell parameters including wall thickness and rounding in cell corners. Here we measured these cell parameters in nest cells of 75 bee and wasp species that vary in diameter and materials (wax, paper, mud, and a combination of mud/paper). There are two ways to increase the strength of honeycomb as the cell diameter increases: (1) increasing wall thickness, which increases weight and materials used, and (2) rounding the corner angles (“corner radius”), which honeybees use to increase comb strength while conserving material. We hypothesized that as nest cells increase in diameter, we would see increases in corner radius and wall thickness, with corner radius more significantly conserving nest material. We also predicted that corner radius and wall thickness would be more important in nests constructed from wax and mud than paper due to the materials’ strengths and stiffnesses. After measuring nests using a Keyence imaging system, we found support for both hypotheses. Bees and wasps show economy of nest material use by using cell geometry rather than added material to increase strength, which offers applications for bio-inspired design and engineering.