2Redback Spider (Latrodectus hasselti)
The redback is another cousin of the black widow L. mactans;
however, this species is not as widespread. It is native to Australia,
but it has spread to New Zealand, Belgium, and Japan through grape
exports. (The spider often builds nests and webs on grape leaves and
inside bunches.) The species is widespread throughout Australia, living
in all of the continent’s varied environments, except for its hottest
deserts and frigid mountaintops. The species is also found in urban
areas, frequently making nests in human dwellings. The redback is
identified by its prominent red stripe or hourglass-shaped mark on its
black-colored back. This mark is more noticeable on female redbacks than
on males.
Redback spiders are not aggressive and are more likely to play dead when disturbed, but a female spider defending her eggs is very likely to bite. Bites also occur when the spider climbs into shoes or clothing and becomes trapped against the victim’s skin when he or she is dressing. Both male and female redbacks are venomous, but most envenomations primarily result from female bites. Only 10-20% of all victims bitten are envenomed. The venom is a mix neurotoxins called alpha-latrotoxins, which produces pain, sweating, rapid heartbeats, and swollen lymph nodes. The spider can moderate the amount of venom it injects, and the severity of these symptoms often depend on how much venom is delivered. More than 250 redback bites are treated each year in Australia, many with antivenin. Researchers and physicians are split on the effectiveness of redback antivenin, with some studies indicating that it was not effective in treating symptoms or relieving pain. Nevertheless, the last human death attributed to redback envenomation occurred in 1956.
Redback spiders are not aggressive and are more likely to play dead when disturbed, but a female spider defending her eggs is very likely to bite. Bites also occur when the spider climbs into shoes or clothing and becomes trapped against the victim’s skin when he or she is dressing. Both male and female redbacks are venomous, but most envenomations primarily result from female bites. Only 10-20% of all victims bitten are envenomed. The venom is a mix neurotoxins called alpha-latrotoxins, which produces pain, sweating, rapid heartbeats, and swollen lymph nodes. The spider can moderate the amount of venom it injects, and the severity of these symptoms often depend on how much venom is delivered. More than 250 redback bites are treated each year in Australia, many with antivenin. Researchers and physicians are split on the effectiveness of redback antivenin, with some studies indicating that it was not effective in treating symptoms or relieving pain. Nevertheless, the last human death attributed to redback envenomation occurred in 1956.
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