What does stirring up a hornets nest mean?

Hornets are wasp-like insects. Their nests are similar to the ones made by bees. Stirring up a hornet’s nest metaphorically means to stir a silent/calm situation into that filled with rage, discord or one with chaos. It also means to provoke the attack of a swarm of spiteful enemies or spirited critics. This metaphor is self-explanatory as when one ‘stirs a hornet’s nest’ the hornets fly out of their nest in a temper and attack the cause of the disturbance.