飞蛾爱好者

The Sneaky Moth can be found atop the Inquest structure on Artificer's Islet. It is located roughly above the 'A' in "Artificer's" on the map, underneath a tall archway on the western wing of The Forge. Pet the moth with your interact key for the achievement.

The achievement lists this NPC as a "gentle moth" instead of a sneaky one.