black widow (n.)

type of poisonous spider (Latrodectus mactans) in U.S. South, 1904, so called from its color and from the female's supposed habit of eating the male after mating (they are cannibalistic, but this particular behavior is rare in the wild). Sometimes also known as shoe-button spider. The name black widow is attested earlier (1830s) as a translation of a name of the "scorpion spider" of Central Asia.