Phi pa (ผีป่า).
            Phi pa means phi of the forest or jungle. There are many kinds of them and they confine themselves to the forest and rarely come to a village or town. If they come it means there is something wrong in the village or town. They come, usually in the form of epidemic disease. Butterflies which come to a village or town in unusual swarms are much dreaded by the people. They believe that butterflies are harbingers of epidemic disease; for swarms of butterflies come from the jungle which is the seat of such disease, especially malaria, called in its popular form "khai pa" (ไข้ป่า) or jungle fever. In Thai a butterfly is called phi sua (ผีเสื้อ) which means a phi with, a lineage or a phi with a germ. The word forms many names of evil. spirits. A giantess or ogress is called "Phi sua yak" or a "yaksha phi sus"; if it has its habitat in a lake or pond, it is called a "phi sua nam" or a water phi sua. A giant moth is also called a phi sua yak.
            The people in towns have had, of course, less experience with phi pa. Out of the many kinds of phi pa, two are perhaps well known through literature. They are the "phi kong koi" (ผีกองกอย) and "phi poang khang" (ผีโป่งค่าง). I knew 'these two phi only in name until I happened to meet a friend of mine who had knowledge of forest lore. He sent me an account of his experiences with these two kinds of jungle phi, which descriptions, with his consent, appeared in the journal of the Fine Arts Department. The following is a brief summary.