Even a worm will turn

"Even a worm will turn" is an English language expression used to convey the message that even the meekest or most docile of creatures will retaliate or seek revenge if pushed too far. The phrase was first recorded in a 1546 collection of proverbs by John Heywood, in the form "Treade a worme on the tayle, and it must turne agayne." At the time “agayne” also meant “against” or “oppose”. It was used in William Shakespeare's play Henry VI, Part 3. In the play, the phrase is uttered by Lord Clifford, killer of Rutland as:
It's been proposed
that this passage from Henry VI was suggested by one in a history by Edward Halle. In that book the Earl of Warwick makes a speech that includes the passage:
In 1641, the following passage in a letter from Edmund Verney to his son Ralph Verney further confirms the proverb's meaning that small affronts can lead to rebellion.
The proverb is also found in other countries.

France

In 1694 the 1st edition of the Dictionnaire de l’Académie française included the proverb with an explanation:
In English "An earthworm shrivels up when you step on it,' to say that there is no man so weak and puny that he does not feel some resentment when he is offended." However in 1694 se rebequer implied more rebel than shrivel.
Earlier in 1592
the proverb appeared in the poem Plainte de l’Autheur durant une sienne longue maladie by Philippes Des Portes. The verse with a translation is shown below:

Germany

In German the expression is: Auch der Wurm krümmt sich, wenn er getreten wird.
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In 1782, in his dictionary of German proverbs, Joachim Blum gave the meaning as:
The earliest surviving record in German is from 1541 in a book of proverbs by Sebastian Franck
Franck recorded three versions of the proverb and listed them under Latin sayings expressing similar ideas.
German writers who used the expression include Goethe,
Schopenhauer and Nietzsche.