Aitvaras and Pukis

Aitvaras are a type of malicious house spirit from Lithuanian mythology. They look like purely black or white roosters with flaming tails while inside the house, and like small dragons outside. When they fly they look like a comet streaking across the sky. Aitvaras hatch from eggs of a 9 to 15 year old rooster. Don't ask how a rooster would lay eggs, although it's a motif I've noticed popping up in mythology occasionally. The aitvaras would serve a family in a household through deceptive means. It would bring wealth and good fortune to the household by stealing from the neighbours. The aitvaras would go on nightly flights to rob them. Owning an aitvaras would inevitably bring strain between the household and the rest of the community. Additionally, the aitvaras would slowly siphon away the souls of the residents, damning them. Once an aitvaras was inside a house it was very difficult to remove. Killing it would be difficult as it would heal as soon as it touched the floor...