Ghost of a flea

Possibly because of feng shuei, carpenters and masons were associated with sorcerers. Proper ritual construction of homes was essential. It was believed that bridge-builders could steal a man's soul by clipping off his queue, or take a woman's soul by clipping a piece of her collar; the stolen soul was placed on a piling of a bridge under construction and hammered into the river-bed, killing the victim but ensuring a sturdy bridge. Soulstealers were believed to operate in gangs, paying petty thieves to collect pigtails, with evil sorcerers lurking somewhere to use the stolen souls.

The Lu-pan-ching was a popular carpentry manual in Ch'ing times; it contained rules for proper ritual construction, but also baleful charms for builders to hide atop rafters or under floors; and also charms to be used against such evil builders. This manual was thought so powerful that when a copy was sold, the bookseller always faced away from the book; anyone who opened the pages had to inflict magical harm on someone, or else himself suffer.