Feldgeister

Feldgeister, or field spirits in English, is a term used for a number of characters within German folklore. They are often related to the harvest and determining the yield.

Roggenmuhme
The Roggenmuhme (also called similar names such as Rogenmühme) is a Feldgeiste whose name translates to "rye aunt". She is described to have breats filled with tar, with some accounts saying the tips are covered with iron. They are said to be so long that she has to put them over her shoulders when she runs. The tips of her fingers spout fire and she holds a birch cane or whip from which she produces lightning. She is also known to change into other animals.

The Roggenmuhme is known to steal children and replace them with changelings.