As a young boy, he told his servants not to kill two snakes. Grateful, the snakes gave Melampus the ability to speak with animals.
Melampus lived in Pylos during the reign of Anaxagoras or possibly Proetus. The prince suffered from a strange malady and the king offered a reward for anybody that could heal him. Melampus killed an ox and talked to the vultures that came to eat the corpse. They said that the last time they had had such a feast was when the king made a sacrifice. They told Melampus that the prince had been frightened of the big, bloody knife and the king tossed it aside to calm the child. It had hit a tree and injured a hamadryad, who cursed the prince with the sickness. The hamadryad told Melampus that he boy would be healed if the knife was taken out of the trunk of the tree and boiled, then the rusty water that resulted dranken by the prince. Melampus followed her directions and demanded two thirds of the kingdom for himself, and one third for his brother, Bias. The king agreed.
Alternate:
When the women of Argos were driven mad by Dionysus, in the reign of Anaxagoras or possibly Proetus, he was brought in to cure them, but demanded a third of the kingdom as payment. The king refused, but the women became wilder then ever, and he was forced to seek out Melampus again, who this time demanded both a third for himself and another third for his brother Bias.
After this there were three kings ruling Argos at any time, one descended from each of Bias, Melampus, and Anaxagoras. Melampus was succeeded by his son Mantius, and his house of Melampus lasted down to the brothers Alcmaeon and Amphilochus, who fought in the Trojan War.
Late in his life, Melampus was kidnapped. In his cell, he overheard two termites talking, claiming they would be finished eating through Melampus' ceiling the next morning. Melampus demanded a move and made such a ruckus that the kidnappers acquiesced. When the ceiling collapsed the next morning, the kidnappers decided he was a prophet and to hold on to him might offend the gods. They let him go.