Redback mating is unlike almost anything else in the genus. Having inserted a palp, the male twists his abdomen forward through roughly 180 degrees and places it against the female's fangs. She begins digesting him where he sits. Around two-thirds of males are consumed.
Research by Maydianne Andrade in the 1990s established what the behaviour returns. Cannibalised males copulate for longer, transfer more sperm and are more likely to be the female's only mate, because a fed female is less receptive to the next male. In a species where a male's chance of ever finding a second female is small, that is not a poor trade.
The female's venom is a latrotoxin, producing the sustained pain, sweating and malaise of latrodectism. An antivenom has been available since 1956. No death was confirmed for decades afterwards, and the few later disputed cases have kept the question open.