The Redback spider, Latrodectus hasselti, is a highly venomous arachnid native to Australia. It is recognized for its distinctive appearance and the medical significance of its bite. Its prevalence in human-inhabited areas makes understanding this spider important. It belongs to the Latrodectus genus, which includes other notorious spiders like the black widow.
Identifying a Redback
The female Redback spider is easy to identify due to her striking appearance. She has a spherical, glossy black body, about 1 centimeter (0.4 inches) long, similar to a large pea. A prominent red or orange stripe runs lengthwise on her upper abdomen, with an hourglass-shaped mark visible on her underside. While this red stripe is characteristic, some females may have incomplete markings or even all-black abdomens. Her slender legs include a first pair notably longer than the others.
In contrast, the male Redback spider is considerably smaller, only about 3 to 4 millimeters (0.12 to 0.16 inches) long. Males are light brown and less conspicuous, often having white markings on their upper abdomen and a paler hourglass mark on their underside. Their smaller fangs mean they are less of a threat to humans, as they may not effectively penetrate human skin.
Where Redbacks Live and Their Habits
Redback spiders are widely distributed across Australia, thriving in various environments, especially near human activity. They prefer dry, dark, and sheltered locations, often establishing webs in sheds, garages, under outdoor furniture, in letterboxes, and even under toilet seats. These spiders are reclusive and primarily nocturnal.
Their webs feature an irregular, tangled, funnel-like structure with strong, sticky threads extending vertically to the ground. These lines ensnare prey, pulling victims into the web. Redbacks predominantly feed on insects, but can also capture larger prey like trapdoor spiders, small lizards, and occasionally small snakes or mice if entangled.
Understanding the Redback Bite
A bite from a female Redback spider can lead to latrodectism, caused by neurotoxic venom. While a bite might initially feel like a minor pinprick, localized pain intensifies and spreads from the bite site within minutes to hours. This pain can become severe, radiating up the bitten limb and sometimes lasting over 24 hours.
Common symptoms include localized sweating around the bite area, indicating envenomation. Other systemic symptoms may develop, such as nausea, vomiting, headache, abdominal pain, muscle weakness, and general malaise. Although Redback bites are rarely fatal, they can cause significant discomfort and require medical attention.
For first aid, clean the bite area with soap and water to minimize infection risk. Applying an ice pack can help reduce swelling and manage pain. Seek medical advice if pain is severe, symptoms worsen, or systemic effects like sweating and widespread pain are present. Antivenom is available and highly effective in treating severe latrodectism, alleviating symptoms and preventing prolonged illness.