To the Vishvedevas it should be offered in open air, and to the Rakshasas and evil spirits the offerings should be made at night.
तथैव विश्वेदेवेभ्यो बलिमाकाशतो हरेत्। निशाचरेभ्यो भूतेभ्यो बलिं नक्तं तथा हरेत्॥