From: Magical Creatures of Hogwarts
The Stair Doxy is closely related to the Regular Doxy but come in different colors from blonde to red as well as multicoloured. This form of Doxy lays upon stairs, preferably in bright sunlight, and trips unsuspecting people and then bites your ankles. They can be placated with a good dose of grilled meat.
Doxy (XXX)- It is also known as a biting fairy, because it has been mistaken for a fairy in earlier times. It has a miniature human form but is covered in thick black hair and extra arms and legs. They have two rows of venomous sharp teeth. If you are bitten, you should take an antidote. These are the creatures the Weasley’s, Harry, and Hermione had to get rid of in the Black house.