Presociality
Among the Vespid wasps, the pressures of predators and parasites selected subsocial behaviour. It is easier to guard the eggs and grubs when the mother wasp stays in her nest to watch over her larva. More so if other adults stay with her. Then the other adults need to collect more food than just for themselves. And so on. It becomes less likely that parasites will be successful in preying on the nest.