A yellowjacket colony runs on a trade. Adult workers cannot process solid protein, so they capture insects, chew them and feed the pulp to larvae. In return the larvae exude a sugary secretion that the adults drink. This trophallaxis keeps foragers fuelled through the growth phase of the colony.
In late summer the queen switches to producing new queens and males, and brood production winds down. The larval sugar supply dwindles, and workers that no longer have anything to feed and nothing feeding them shift to seeking carbohydrate directly: fallen fruit, tree sap, sweet drinks and rubbish. This is why late-season wasps seem newly aggressive around food when they largely ignored it in July.
The entire worker force dies with the first hard frosts. Only mated new queens overwinter, and each spring nest is built from scratch by one of them. Old nests are not reoccupied, which is why an abandoned paper nest in a loft poses no risk the following year.