Stingless bees of the genusTetragonulaconstruct a brood comb with a spiral or a target pattern architecture in three dimensions. Crystals possess these same patterns on the molecular scale. Here, we show that the same excitable-medium dynamics governs both crystal nucleation and growth and comb construction inTetragonula, so that a minimal coupled-map lattice model based on crystal growth explains how these bees produce the structures seen in their bee combs.