The Myrmidons (or Μυρμιδόνες, the name literally means "ant-people") were an ancient nation of Greek mythology. The story of their origins was first mentioned by the poet Ovid. Initially, the Myrmidons were simple worker ants on the island of Aegina.
Myth of the repopulation of Aegina
Hera, queen of the gods, sent a plague to kill all the human inhabitants of Aegina because the island was named for one of the lovers of Zeus. King Aeacus, a son of Zeus and the intended target of Hera along with his mother, prayed to his father for a means to repopulate the island. As the ants of the island were unaffected by the sickness, Zeus responded by transforming them into a race of people, the Myrmidons. They were fierce and hardy as ants, and intensely loyal to their leader.
After a time, Aeacus exiled his two sons, Peleus and Telamon, for murdering their half-brother, Phocis. Peleus went to Phthia and a group of Myrmidons followed him to Thessaly. Peleus's son, Achilles, brought them to Troy to fight in the Trojan War. They feature as the loyal followers of Achilles.
Another tradition states that the Myrmidons had no such remarkable beginnings, but were merely the descendants of Myrmidon, a Thessalian nobleman, who married Peisidice, the daughter of Aeolus, king of Thessaly. Myrmidon was the father of Actor and Antiphus. As king of Phthia, Actor (or his son) invited Peleus to stay in Thessaly.