Gravity-independent orientation of honeycomb cells

Honey bees have long been assumed to build their comb with the cells in eit her of two preferred orientations with respect to gravity ("vertical" or "h orizontal"). I show here that these typical cell orientations in fact deriv e from substrate orientation and a simple building rule, rather than the in fluence of gravity itself. When bees were induced to build comb on substrat es at four different orientations with respect to gravity, they always made cells with one vertex pointing directly toward the substrate. This produce d horizontal and vertical cells on vertical and horizontal substrates, resp ectively, but yielded intermediate orientations on oblique substrates. The apparent preference for vertical and horizontal cells may simply reflect su bstrate orientation in the rectilinear hives from which cell measurements h ave been taken.