OE hnitu came from the PIE root *knid, *k'nid, *sknid 'louse, egg of the louse, nit'. So, it's safe to say that the Proto-Indo-Europeans knew about lice, nits, and the louse reproductive cycle. I see the word survives in Armenian anic, Albanian thëni, Greek konis (konidos), Middle Irish sned, Welsh nedd pl., Breton nez.