Alp-Luachra | Joint Eater of Irish Folklore

The Alp-Luachra is a parasitic fairy from Irish folklore, a "joint-eater" that infests humans, appearing as a newt or louse, consuming the "quintessence" or best part of their food, causing extreme hunger, weakness, and wasting away, but can be expelled by eating salty meat and lying by a stream to lure it out for water, according to tales collected by Robert Kirk and Douglas Hyde. 

What it is

• A mischievous, often malevolent fairy type, also called a "Just-Halver".
• It's a parasitic entity, like a magical tapeworm, that lives inside a host, usually entering via the mouth near water.
• It looks like a newt or louse and consumes the vital essence (marrow/pith) of food, not the bulk, making the person feel perpetually hungry. 

Effects on humans

• Victims never gain weight, becoming gaunt and weak, despite eating plenty.
• It can reproduce inside the host, increasing the parasitic load. 

How to get rid of it (according to folklore)

• Eat large amounts of salted meat without drinking.
• Lie down with your mouth open over a stream or spring.
• The fairy, driven by thirst, or its offspring, will jump out to drink, revealing themselves. 

Cultural context

• Represents fears of unexplained illness, parasites, and gluttony.
• Tales documented in works like Robert Kirk's Secret Commonwealth and Douglas Hyde's Beside the Fire.