Belief in the tlahuelpuchi (plural: tlahuelpocmimi ) is prominent in at least the Mexican state of Tlaxcala. Most typically, the tlahuelpuchi is a woman born with a curse.

When she enters puberty and has her first menstruation, she craves blood.

At night she transforms into an animal such as a cat, a dog, a turkey, a vulture, or a flea. In some versions of the belief, she leaves her legs behind in the form of a cross before she goes out in animal to seek her victims.

Her favorite victims are infants but she also attacks adults and cattle. Most typically, a tlahuelpuchi only requires blood once a month. But according to some versions of the belief, she thirsts for blood four times each month. The tlahuelpocmimi join together in societies and make a pact to not infringe upon each other’s territories while seeking for prey.

A tlahuelpuchi will also not prey upon her family or neighbors in order to remain incognito. It is difficult to detect a tlahuelpuchi. But one test is to offer an enchilada containing garlic to a woman suspected of being a tlahuelpuchi.

For more details about the tlahuelpuchi see The Vampire Book by J. Gordon Melton (Visible Ink Press, 1994, 1999) or Blood Sucking Witchcraft by H. G. Nunti and J. M. Roberts (University of Arizona Press, 1993).