Lykus was the king of an island of the Propontis. Lykus' kingdom had often been attacked by Amykus, so when he learned that one of the Argonauts had finally killed Amykus Lykus was happy to receive them. While they were out gathering straw, a wild boar attacked Idmon fatally wounding him.

Ancient Text

"Lycus, king of an island of the Propontis, received the Argonauts hospitably, grateful because they had killed Amycus, who had often attacked him. While the Argonauts were staying with Lycus, and had gone out to gather straw, Idmon, son of Apollo, was wounded by a wild boar and died."
- Hyginus, Fabulae, 18