SB 4.10.28
evam-vidhany anekani
trasanany amanasvinam
sasrjus tigma-gataya
asurya mayayasurah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The demon Yaksas are by nature very heinous, and by their demoniac power of illusion they can create many strange phenomena to frighten one who is less intelligent.