"eating only one kind of food," by 1849, of insects, from mono- "single" + -phagous "feeding on, eating." Greek monophagos meant "eating once a day."
Entries linking to monophagous
mono-
word-forming element of Greek origin meaning "one, single, alone; containing one (atom, etc.)," from Greek monos "single, alone," from PIE root *men- (4) "small, isolated."
-phagous
word-forming element meaning "eating, feeding on," from Latin -phagus, from Greek -phagos "eater of," from phagein "to eat," literally "to have a share of food," from PIE root *bhag- "to share out, apportion; to get a share."