Itys was the son of King Tereus and his wife Procne, in Greek mythology. To take revenge from her husband, Procne killed their son Itys, boiled him and served him as a meal to Tereus. ...

What did Procne do in revenge?

Procne sought revenge by serving up her son Itys for Tereus's supper. On learning what Procne had done, Tereus pursued the two sisters with an ax. But the gods took pity and changed them all into birds—Tereus into a hoopoe (or hawk), Procne into a nightingale, and Philomela into a swallow.

Why did Philomela kill their son?

Rendered unable to speak because of her injuries, Philomela wove a tapestry (or a robe) that told her story and had it sent to Procne. Procne was incensed and in revenge, she killed her son by Tereus, Itys (or Itylos), boiled him and served him as a meal to her husband.