Under extremely rare conditions, there have been documented cases of human intestinal myiasis of the rat-tailed maggot (larva of "Eristalis tenax"). Zumpt proposed a hypothesis called "rectal myiasis". During open defecation in the wilderness, flies attracted to feces may deposit their eggs or larvae near or into the anus, and the larvae then penetrate further into the rectum. The larva can survive, feeding on feces at this site, as long as the breathing tube reaches out from the anus, which is quite rare.