File:Fig 2. Pentastoma life cycle.jpg

Life cycle of Pentastomidae. The normal life cycle is indicated by the blue arrows: the adult parasites are found in the upper respiratory tract of reptiles, birds or mammals (1). There, the male and female worms lay eggs that are expulsed of the final hosts through the upper airways or the digestive system (2). The eggs may then be ingested by an intermediate host in which larvae hatch, break through the intestinal wall and form cysts in various body locations (3). The cycle ends up when the intermediate host is eaten by the definitive host, in which larvae reach the upper respiratory tract by crawling from the esophagus and grow to become adult worms (4). The red arrow shows that humans can accidentally become intermediate hosts (5).