They are only found in the ashlands on Solstheim.
Ash hoppers will attack the Dragonborn if they get too close to their position, rising out of the ash. They attack in groups or sometimes alone, running into melee range. Once dead, they will fall apart like skeletons. If their health gets too low, they will attempt to flee from combat. They may also afflict the Dragonborn with Droops. A group of Ash hoppers might attack each other if they emerged from the ash but hasn't detected the Dragonborn.