Black Belly of the Tarantula-Giancarlo Giannini, Claudine Auger-1971 IMDb 6.3/10

Inspector Tellini investigates serial crimes where victims are paralyzed while having their bellies ripped open with a sharp knife, much in the same way tarantulas are killed by the black wasp. As suspects keep dying, the inspector directs his attention to a spa all the victims had a connection with.