Hexamerins are hemocyanin-related haemolymph proteins that are widespread in insects and may accumulate to extraordinarily high concentrations in larval stages. Hexamerins were originally described as storage proteins that provide amino acids and energy for non-feeding periods. However, in recent years other specific functions like cuticle formation, transport of hormones and other organic compounds, or humoral immune defense have been proposed. During evolution, hexamerins diversified according to the divergence of the insect orders. Within the orders, there is a notable structural diversification of these proteins, which probably reflects specific functions. In this paper, the different possible roles of the hexamerins are reviewed and discussed in the context of hexamerin phylogeny., Thorsten Burmester, and Lit