tarantula n.

1782, "peasant dance popular in Italy," originally "hysterical malady characterized by extreme impulse to dance" (1630s), epidemic in Apulia and adjacent parts of southern Italy 15c.-17c., popularly attributed to (or believed to be a cure for) the bite of the tarantula. This is likely folk-etymology, however, and the names of the dance and the spider more probably share an origin in Taranto, the name of a city in southern Italy (see tarantula). Used from 1833 to mean the style of music that accompanies this dance, usually in 6/8 time, with whirling triplets and abrupt major-minor modulations. Related: Tarantism.

Those who were bitten generally fell into a state of melancholy, and appeared to be stupified, and scarcely in possession of their senses. This condition was, in many cases, united with so great a sensibility to music, that at the very first tones of their favourite melodies, they sprang up, shouting for joy, and danced on without intermission, until they sank to the ground exhausted and almost lifeless. [Babington's translation of J.F.C. Hecker, "The Epidemics of the Middle Ages," London, 1859]