The redback spider (Latrodectus hasselti) is a highly venomous spider that is also known as the Australian black widow. Likely originating in South or Western Australia, most redback spiders are the size of a large pea. Females are generally larger than males, as females tend to be 1 cm in length, while males are only 3 to 4 mm in length. A female is easily identified by her black body with a red or orange stripe on the upper abdomen. Additionally, young females have additional white markings on the underside of the abdomen. Male redback spiders are often light brown in color and have white markings on the abdomen. Both male and female redback spiders have slender legs. Redback spiders are mostly nocturnal and feed on insects, but may also feed on king crickets, male trapdoor spiders, small lizards, and any other animal that gets trapped within their webs. The spiders use venom to kill prey captured within their webs. Redback spiders live in areas that provide an adequate food supply, shelter, and warmth, which can include near or inside buildings or homes.
Habitat and Range
Redback spiders are believed to have originated in South or Western Australia, and are now common all over Australia, as well as parts of Southeast Asia and New Zealand. Additionally, the redback spider can also be found in Belgium, the United Arab Emirates (UAE), Iran, England, and Japan. The spider species prefers to inhabit places where humans live, and often build webs in logs, on rocks, sheds, junk-piles, shrubs, and toilets. Redback spiders can live in a wide range of habitats, from forests to deserts, and prefer drier areas. They prefer summer to winter and are rarely observed during the winter season.
How Dangerous Are Redback Spiders to Humans?
Redback spiders rarely attack humans. Since they rarely leave their webs, attacks on humans are uncommon unless a person comes in direct contact with a female redback spider, as it is only the female bite that is considered dangerous. In such cases, the female spider may only give a warning bite, without injecting venom, as they are rarely known to be aggressive. However, the venom released by females contains alpha-latrotoxin venom that has the potential to cause death in humans and animals. A venomous bite releases poison directly to the nerves, resulting in the depletion of neurotransmitters. Symptoms of a bite include nausea, vomiting, headaches, abdominal pain, and chest pain. Severe bites can also result in sweating and increased blood pressure. Fortunately, antivenom exists and is effective if administered in a timely manner. Since interactions between redback spiders and humans are minimal, venomous bites are also rare.