I like to think the blindfolded girl tied to a tree is squatting without panties on. It adds to her sexual tension for her to wonder if the slight tickle she feels in her genital area from time to time is just the tips of blades of grass brushing against her, or whether an ant or two is exploring her terrain and may report its findings to the rest of the colony. Doubtless this will motivate her more to alacrity in her duties than the eventual coming of nightfall.