Leslie Massey
The Australian black widow, also known as the redback spider, is a highly venomous spider species believed to originate in Australia. It is now found in Southeast Asia, New Zealand, and the United States, with colonies outside Australia. In Australia, the redback spider is found across the continent, living in various environments, including disturbed and urban areas, as long as there is food, shelter, and warmth for breeding.
| Characteristics | Values |
|---|---|
| Common Name | Black Widow Spider |
| Scientific Name | Latrodectus hasselti |
| Other Names | Australian Black Widow, Redback Spider |
| Habitat | Australia-wide, Southeast Asia, New Zealand, the United States |
| Habitat Type | Warm, sheltered locations, near human residences, disturbed and urban areas |
| Food | Insects, spiders, small vertebrates |
| Behaviour | Nocturnal, builds untidy webs |
| Danger to Humans | Yes, venomous bite |
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What You'll Learn
The Australian black widow is the Latrodectus hasselti species
The Australian black widow, also known as the redback spider, is the Latrodectus hasselti species. It is a highly venomous spider believed to have originated in Australia but now found throughout Southeast Asia and New Zealand. It has also been discovered in packing crates in the United States, with colonies established outside Australia. The adult female redback is easily recognised by her spherical black body with a prominent red stripe on the upper side of her abdomen and an hourglass-shaped red/orange streak on the underside. Females typically have a body length of about 10 millimetres, while males are significantly smaller, measuring only 3-4 millimetres in length.
The redback spider is mainly nocturnal, with the female staying concealed during the day and spinning her web at night. She usually remains in the same location for most of her adult life. The web is a gum-footed tangle web, an irregular-looking tangle of fine yet strong silk. The threads appear random but are strategically placed for support and to trap prey. The rear of the web forms a funnel-like retreat area where the spider and egg sacs are found. This area has vertical, sticky catching threads that lead to ground attachments, acting as tripwires to alert the spider to prey or threats.
The redback spider is a member of the cosmopolitan genus Latrodectus, the widow spiders. The taxonomy of this genus was historically unclear due to the difficulty of using morphology to determine subdivisions. However, modern genetic studies have split the genus into approximately 30 species, with the redback recognised as a distinct species. Swedish arachnologist Tamerlan Thorell described the redback spider in 1870, naming it Latrodectus hasseltii in honour of his colleague A.W.M. van Hasselt.
The redback spider is often confused with spiders in the genus Steatoda, known as false widow spiders, due to their similar appearance. The presence of latrotoxin in their venom makes black widow bites potentially dangerous, causing systemic effects such as severe muscle pain, abdominal cramps, diaphoresis, tachycardia, and muscle spasms. However, despite their infamy, Latrodectus bites rarely result in death or serious complications. Only female bites are dangerous to humans, as they possess unusually large venom glands.
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Redback spiders are found across Australia
Redback spiders, also known as the Australian black widow, are found across Australia. They are believed to have originated in Australia but have also been found in Southeast Asia, New Zealand, and the United States. Redbacks are highly venomous spiders that are easily recognised by their spherical black bodies and prominent red stripes. They are mainly nocturnal, spinning their webs at night and preferring warm, sheltered locations near or inside human residences.
Redback spiders are widespread throughout Australia, living in various environments, including disturbed and urban areas. They can be found in all states and territories of Australia, from coastal regions to inland areas. They are particularly common in urban areas, often making their nests in and around human dwellings. Redbacks are adaptable and will live anywhere as long as there is adequate food, a sheltered web site, and a warm enough environment for breeding.
The female redback spider typically remains concealed during the day, spinning her web at night. She spends time producing up to ten round egg sacs, each containing approximately 250 eggs. The webs are untidy-looking tangles of fine but strong silk, strategically placed for support and entrapment of prey. The rear portion of the web forms a funnel-like retreat area where the spider and egg sacs are found, with vertical sticky threads acting as tripwires to alert the spider to any prey or threats.
Redback spiders are closely related to the black widow spiders commonly found in North America. While they were once considered a subspecies of the black widow, genetic research has revealed that they are, in fact, a distinct species. The main difference between the two is the presence of a red dorsal stripe on the redback, which is absent in the black widow. The venom of the redback spider is not as well-studied as that of the black widow, but it is believed to contain similar toxins.
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Redback spiders are a close relative of the black widow
Redback spiders, or Latrodectus hasselti, are a species of highly venomous spiders believed to originate in Australia. They are also found in Southeast Asia, New Zealand, and the United States. Redbacks are a close relative of the black widow spiders and belong to the cosmopolitan genus Latrodectus, the widow spiders.
The adult female redback spider is easily recognised by its spherical black body with a prominent red stripe on the upper side of its abdomen and an hourglass-shaped red/orange streak on the underside. The female redback's body length is about 10 millimetres, while the male is much smaller, at only 3-4 millimetres. The male redback spiders are brown, while the male black widow spiders are black or grey.
Redback spiders are mainly nocturnal, and the female redback lives in an untidy web in a warm, sheltered location, commonly near or inside human residences. They are less common during the winter months. Redback spiders are less aggressive than black widow spiders and are more likely to be found near human populations, while black widows prefer remote areas.
Redback spiders prey on insects, spiders, and small vertebrates that become ensnared in their webs. Their webs are strategically placed for support and entrapment of prey, with vertical, sticky threads that act as tripwires to alert the spider to the presence of prey or threats.
Redback spiders are closely related to the New Zealand katipō, another member of the Latrodectus genus. While redback spiders were once considered a subspecies of black widow spiders, recent DNA research has indicated that they are distinct species.
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Redback spiders are also found in New Zealand, Belgium, and Japan
The redback spider, also known as the Australian black widow, is believed to originate in Australia. However, it has also been found in other parts of the world, including New Zealand, Belgium, and Japan.
In New Zealand, the redback spider was introduced in the early 1980s and has since established small colonies, particularly in drier areas and around Central Otago in the South Island and New Plymouth in the North Island. They are often found in outbuildings and are frequently intercepted by quarantine authorities, sometimes among steel or car shipments.
In Belgium, redback spiders have been reported to exist in colonies established in greenhouses.
Japan has also seen a significant presence of redback spiders, with the first discovery in Osaka Prefecture in September 1995. The spiders are believed to have arrived in the country by attaching themselves to containers shipped from overseas, including cargoes of wood chips. Over time, they have spread across nearly the entire country, found in 45 out of 47 prefectures as of 2023. Their dispersal mechanisms within Japan are unclear, but their small size and ability to hide in roadside ditches and planters have likely contributed to their expansion.
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Redback spiders are nocturnal and live in untidy webs
The redback spider, also known as the Australian black widow, is a highly venomous spider species. It is mainly nocturnal, with the female redback staying concealed during the day and spinning her web at night. The redback spider web is a gum-footed tangle web, an irregular-looking tangle of strong silk that forms a funnel-like retreat area for the spider and her egg sacs. These webs are often untidy, with leaves or debris included, and can be found in dry, sheltered locations near human residences, such as among rocks, logs, shrubs, junk piles, sheds, or even toilets.
Redback spiders favour proximity to human habitation and are found throughout Australia, with colonies also established outside Australia in Southeast Asia, New Zealand, and the United States. They are less common during the winter months and prefer warmer temperatures for breeding. Redback spiders are attracted to areas of human activity, where they can find insect prey attracted to food scraps and lighting. They are particularly common in disturbed and urban areas.
The female redback is easily recognised by her spherical black body with a prominent red stripe on the upper side of her abdomen and an hourglass-shaped red/orange streak on the underside. She typically has a body length of about 10 millimetres, while the male is significantly smaller, ranging from 3 to 4 millimetres in length. The male redback does not construct a web and instead searches for a female to mate.
Redback spiders are known for their venomous bites, which can be dangerous, especially from female spiders. However, due to their small jaws, many bites are ineffective, and antivenom has been available since 1956. Bites typically result in pain, sweating, nausea, and vomiting. The venom acts as a neurotoxin, affecting the nerves and causing a release and depletion of neurotransmitters.
To prevent redback spiders from entering homes, pest control measures such as insecticide spray treatments around the perimeter and potential hiding places are recommended. These treatments can be applied once or twice a year, depending on the exposure to rain and sun.
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Frequently asked questions
The Latrodectus hasselti, commonly known as the Australian black widow or redback spider, can be found all over Australia, except for the continent's hottest deserts and coldest mountaintops. They are especially common in disturbed and urban areas, in association with human habitation.
The female Australian black widow is known for its spherical black body with a prominent red stripe on the upper side of its abdomen and an hourglass-shaped red/orange streak on its underside. The male is much smaller, measuring 3-4mm in length, while the female is about 10mm long.
The female Australian black widow is mainly nocturnal, living in an untidy web in a warm, sheltered location, commonly near or inside human residences. They are often found under furniture or in other dark places inside houses and are very common in urban gardens.
Yes, the Australian black widow is a highly venomous spider. Bites from this spider may cause headaches, nausea, and small localized skin blisters. However, antivenom is available and has been shown to improve symptoms.
