nitter

noun

1. (archaic)A louse that deposits nits on horses.

   “[The bots] were hatched, into (what is called in the country) a horse-bee or nitter.”

   “The last three species are the nitters so well known in this country; particularly the leg and throat nitters. It is the received opinion that the nits on the legs of horses, are taken into the mouth of the horse, conveyed into the intestines, and at length become the bot larva.”

   “If the "throat nitter" (Œ veterinus) is the true bot however, […] it must be evident that the remedy proposed […] is at least doubtful […]”