Black Widow vs Redback Spider: Key Differences & Which Is Deadlier
Black Widow and Redback Spider are both venomous Latrodectus spiders; the former lives in the Americas, the latter in Australia and New Zealand.
People mix them up because females of both sport a red hourglass and deliver neurotoxic bites, so “deadly Black Widow” headlines often show the wrong spider.
Key Differences
Black Widow females reach 13 mm, favor woodpiles and sheds across North America, and their venom causes severe muscle cramps. Redbacks are slightly smaller (10 mm), build messy webs under Aussie toilet seats and mailboxes, and produce alpha-latrotoxin that triggers prolonged pain and sweating.
Which One Should You Choose?
In a hypothetical duel, Redback venom packs a higher LD50 for mammals; untreated bites kill more often. Both have effective antivenoms, yet Redback antivenom is used far more, hinting at greater real-world danger. Bottom line: avoid both, but Redback edges it on deadliness.
Can a bite kill a healthy adult?
Extremely rare; antivenom and modern ICU care have cut fatalities to near zero.
Do males bite?
Both male spiders are tiny and possess weak venom; human envenomations come almost exclusively from females.