"tiny animal, minute arachnid," Old English mite, from Proto-Germanic *miton (cf. Middle Dutch mite, Dutch mijt, Old High German miza, Danish mide) originally meaning perhaps "the cutter," in reference to its bite, from Proto-Germanic *mait- (cf. Gothic maitan, Old High German meizen "to cut"), from PIE root *mai- "to cut" (see maim). Or else its original sense is "something small," and it is from PIE *mei- "small," in reference to size (see minus).
"little bit," mid-14c., from Middle Dutch or Middle Low German mite "tiny animal," from Proto-Germanic *miton-, from PIE *mei- "small" (see minus), and thus probably identical with mite (n.1). Also the name of a medieval Flemish copper coin of very small value, proverbial in English for "a very small unit of money," hence used since Wyclif to translate Latin minutum from Vulgate in Mark xii:43, itself a translation of Greek lepton. French mite (14c.) is a loan-word from Dutch.
mite 1 (mīt)
Any of numerous small or minute arachnids of the order Acarina, certain species of which are parasitic on animals and plants, infest stored food products, and in some cases transmit disease.
contraction of minute, from the Latin minutum, the translation of the Greek word lepton, the very smallest bronze of copper coin (Luke 12:59; 21:2). Two mites made one quadrans, i.e., the fourth part of a Roman as, which was in value nearly a halfpenny. (See FARTHING.)