The first tarantula was not the hairy giant most people picture. It was a wolf spider from the heel of Italy.
The name comes from Taranto, a seaport in southern Italy where the spider was common. Etymonline traces English tarantula, first recorded in the 1560s, through Medieval Latin tarantula and Italian tarantola. The city was Tarentum in Latin and Taras in Greek, a name of uncertain origin. The spider it named is the wolf spider Lycosa tarantula. Etymonline says its bite is only slightly venomous.
That spider became famous for an illness it probably did not cause. Etymonline describes a dance-compulsion epidemic in Apulia and nearby parts of southern Italy from the 15th to 17th centuries. The Wellcome Collection says the condition was described as early as the 11th century and lasted well into the 20th. People blamed the spider's bite. Sufferers felt fatigue, apathy and malaise, which could deepen into a catatonic state. A female sufferer was called a tarantata.
The cure was music. Musicians played fast, lively tunes, and the patient leapt up and danced, sometimes for days. Those tunes later became the tarantella. Sufferers also honored St Paul, patron of people bitten by venomous creatures, at his church in Galatina.
Modern scholars do not blame the spider. The Wellcome Collection notes that the Apulian tarantula has no more venom than a bee's sting. The anthropologist Ernesto de Martino, who studied tarantism in the 20th century, concluded that venom was not the real cause. Women in unhappy marriages, or recently widowed, were especially likely to be affected. The dance gave them release and the support of their community.
Even the link between the dance and the bite is doubtful as etymology. Etymonline calls it likely folk etymology. It says the dance and the spider more probably share a name simply because both came from Taranto.
Then the name traveled. By 1794 English was using tarantula for the large hairy spiders of the warmer Americas. The Italian wolf spider kept its place in the scientific name, Lycosa tarantula, while the common name moved across the Atlantic.