EastScape Wikibuilt from the game itself
Star Moth egg
“Put it in a hatchery on your island with 3 Ordinary pet food: a Star Moth in 48 hours. Only from the Star Tent. Bound: it can't be traded, sold or dropped.”
Hatches
Hatches into 
Star Moth in your island's hatchery, in 48 hours. It comes from the Star Tent in Cloudreach.
Sold by
The Star Tent, in Cloudreach: 8,000 Star Fragments. World events.
Can't be traded. Your star moth egg can't change hands.