Matteo A Negroni, Adria C LeBoeuf 

Social insects are known for reproductive and behavioral division of labor, but little attention has been paid to metabolic forms of division of labor. Metabolic division of labor is the partitioning of complementary metabolic tasks between individuals within the colony, and it is widespread in social insects. Here we pinpoint trophallaxis, trophic eggs and cannibalism as the most well-studied transfers underlying metabolic division of labor in social insects and discuss their evolution. We argue that metabolic division of labor underpins fundamental aspects of colony physiology and may be a necessary feature of superorganismal systems, impacting many life history traits. It is critical to investigate metabolic division of labor to better understand major evolutionary transition(s) to superorganismality in social insects.