An old Russian spring holiday which took place on the seventh (sometimes the eighth) week after Easter. The most important day of this week was Semik and the deity most associated with it is Simargl.
The Rusalki were believed to be at their most dangerous during this time, and were supposed to have left their watery depths for the fields and forests. Peasant women sometimes hung offerings to appease them. A cross, a magic circle, incense, garlic, wormwood, a pin or poker and verbal charms were meant to render the rusalki harmless.
The holiday has been Christianized and now lives on as Trinity Week.