As the colour of life green is feminine. In the west, the connection between the colour green and the feminine is almost forgotten. This idea is still alive in China.
Heller (1989)

The belief in vampires or Beregyni is common among all Slavic peoples. The basic meaning of the word seems to be ‘flying creature’ (Russian parit = to hover; pero = feather, plume). A vampire is understood to mean the spirit of a dead person or a corpse brought to life by the evil spirit. The vampire sucks the blood of people and animals, which results in death. Belief in vampires has developed strongly, especially in the Balkans and among the Ukrainians. A vampire is rendered harmless by opening the grave and piercing the corpse with a hawthorn branch, after which the corpse is burned.

The vampire appears in many guises. Sometimes he is hairy like a dog, with bloody eyes and teeth. It is also widely believed that he has no bones and is only a sack filled with blood. This is created when the devil rips off the skin of a corpse and blows it up.

The vampires or Beregyni grew out of the cult of the ancestors, the oldest stage of Slavic paganism dating back to the earliest antiquity, to the very origins of human culture. Originally they are mainly female nymphs and spirits of the dead. The deepest roots of the clan god couple (Rod-Rozanica, Artemid-Artemis, Isis-Osiris, etc.) therefore reach to the death cult.

(Vyncke, 1969)