(Image: Hofberg 169)
In Norse legend, the Huldra or Huldrer is a type of troll that takes the form of an attractive young person. The Huldra is a female troll, the Huldrer a male one, and Huldre or Huldrefolk covers the entire race of trolls. They look exactly like normal people, except for the long cow tails that may peek out of their clothes. However, it is very easy for a Huldre to conceal this tail and to impersonate a normal human. Huldra are said to be much more dangerous to young men than Huldrer are to young women, but both male and female will trick an unsuspecting youth into falling in love with them. If a Huldre ever marries, it loses its cow tail and becomes even harder to detect. When they had successfully entrapped their victim, the Huldre dance with them all night, leaving the human dead from exhaustion in the morning (Asala 110-116).
Since the Huldrefolk trick humans into falling in love with and marrying them, they can serve as a sort of warning against falling in love too easily or against trusting people too easily. In addition, the seemingly small detail that the Huldra are more dangerous implies there is a need for greater distrust of women than of men.