"The Butas are attendants of Shiva, who as God of Death was their king. These malign spirits are propitiated by offerings strewn on the ground at the time of the Balinese festivals, and especially at Nyepi, the Feast of Purification, which occurs at the Spring equinox in march and is supposed to mark the end of the rainy season, which is a time of disease in Bali" - M Dunningham