Ants

 NY Times: Ant Milk: It Does a Colony Good Everything in the ant hill seems to need the liquid secretions from members of the colony that are in their pupal stage. By Joshua Sokol

And if newly hatched larvae don’t get to drink it, they’re less likely to survive. As for what the adults get for consuming the stuff themselves, that’s still unclear, but early studies show it contains hormones and neuroactive compounds.