pediculosis (n.)

"lice infestation," 1809, with -osis + Latin pediculus, diminutive of pedis "a louse," said in some sources to be akin to pedere "to break wind" (see petard) on notion of "foul-smelling insect" [Watkins]. But de Vaan traces it to a PIE *pesd- "annoying insect" and compares Avestan pazdu- "beetle, maggot." Pedicule "louse" is attested in Middle English (early 15c.).