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Redback Spiders: Australia’s Notorious Spider

redback Spider 1

Table of Contents

Sharon McCulloch


  • Redback spiders are highly venomous and their bites can be deadly, but effective antivenom is available.
  • Females are larger with a black body and a red stripe on the abdomen, while males are smaller and lighter in colour.
  • Redback spiders are native to Australia but have been found in other countries as well.
  • They prefer human structures as habitats and hide in dark, sheltered areas.
  • Redback spiders build irregular webs with adhesive strands to catch prey and protect themselves.
  • In addition to providing hands-on training, a first aid course or first aid certificate online can also help you build your confidence and develop a calm and composed approach to high stress situations like a spider attack.

Australia has a reputation for dangerous creatures. Our beaches are notorious for Great White Sharks, Blue Ringed Octopuses, Box Jellyfish, and even crocodiles in the tropics. The bush has a similarly fearsome reputation, with Dingos and six of the twelve most venomous snakes in the world. Even some of our cute wildlife has a deadly side, with Koalas having massive claws and Platypuses having highly poisonous spurs on their heels.

Despite this, the famous redback spider is probably one of the most iconic deadly Australian creatures – not least because of its notorious fondness for hiding under toilet seats.

What Is A Redback Spider?

The redback is one of the world’s most venomous spiders and shares the title of Australia’s most venomous spiders with the Sydney Funnel Web and is closely related to the venomous black widow spider found in the United States.

What Does A Redback Spider Look Like?

Redback Spiders are easily identifiable due to their unique physical characteristics. The adult female Redback Spider (Latrodectus hasseltii) has a black body with a conspicuous red stripe on the upper abdomen that resembles an hourglass shape. The female measures between 1 cm to 1.5 cm in body length, and she possesses relatively long, slender legs. 

In contrast, the male Redback Spider is smaller than the female, measuring between 3 mm to 4 mm in body length. The male’s body is generally lighter in colour with white markings and does not have the noticeable red stripe on the abdomen.

Both female and male Redbacks feature a characteristic rounded abdomen and a small, oval-shaped cephalothorax (head and thorax). While their physical appearance may vary slightly, Redback Spiders are typically hairless with a glossy appearance.

Redback Spider Size

The Redback Spider (Latrodectus hasseltii) is a relatively small spider, with females typically measuring between 1 cm to 1.5 cm in body length, while males are smaller, ranging from 3 mm to 4 mm in body length. The female Redback Spider is easily recognisable due to its distinctive black body with a prominent red stripe on the upper abdomen, while the male is generally smaller and lighter in colour with white markings.

Redback Bite

Would you know how to respond to a spider bite? First aid training can teach you what to do.

The redback – known to scientists as Latrodectus Hasselti – is a particularly distinctive spider. They have long, spindly legs and large, distinctively spherical abdomen – often the size of a large pea, but sometimes as large as a blueberry. The body is usually jet-black and shiny, with a characteristic red stripe on the back of the abdomen from which the spider gets its name. This makes it one of the world’s most recognisable spiders, lending its name and iconic colour scheme to various brands and sporting teams.

In some cases, a redback’s body can be browner in colour, and the stripe can have more of an orange tinge.

For many years, scientists believed the redback to be closely related to widow spiders such as the black widow, but recent research has found them to be a distinct species native specifically to Australia – related more closely to the New Zealand Katipo spider.

It’s worth knowing that the description above is specific to the female redback spider – the best known. The male redback is considerably smaller, at around a quarter the size of the female. It also doesn’t have the large abdomen or red back markings for which the species is famous. They’re also far less venomous than the females and not dangerous to humans – hence they don’t get much press.

Where Does The Redback Spider Live?

Originally native only to parts of South Australia and Western Australia, the redback can now be found in every state across Australia. There have also been colonies discovered in Papua New Guinea, New Caledonia, New Zealand and they have even been found in Europe, Japan and America – most likely transported there accidentally by humans.

Redbacks are not migratory – they set up shop in one specific hunting ground and remain there most of their lives. In the bush, this would generally be in a dark hollow in a cluster of rocks or a hollow branch. However, redbacks are incredibly well adapted to (and show quite a preference for) human buildings and structures – which have an abundance of hiding places suited for them. In particular, their fondness for hiding under toilet seats has become something of an Australian cliché.

This is probably why the redback has spread so widely and become common since European settlement – our homes and buildings provide them with the perfect habitat. It’s also why redback spider bites are a reasonably common occurrence in Australia.

How Dangerous Is A Redback Spider?

The bad news is that, as mentioned above, the female redback is one of the world’s most venomous spiders and one of the few spiders known to have killed humans with a bite. Its venom is highly neurotoxic – meaning it attacks the nervous system. This causes intense pain, and in extreme cases, can disrupt the nerve signals enough to cause paralysis and even death.

The good news is that since the early 1950s, we’ve had an effective antivenom available. Since then, only one person (a Sydney man in 2016) has died of a redback spider bite in Australia. He’s also the only person in Australia to die of any spider bite since Funnel Web antivenom became available in the 1980’s.

That’s worth remembering – Australia has only had a single fatal spider bite in the last forty years. But it’s also worth remembering that death was a redback spider bite!

Despite their potent venom, redback spiders aren’t particularly aggressive. They prefer to hide from threats. Most bites occur when humans accidentally disturb their hiding places and possibly dislodge them. They also have relatively small fangs, so biting a human isn’t super-easy for them – our skin is quite thick from their perspective, and many redback bites on humans have little effect as they don’t puncture the skin.

What Does A Redback Spider Bite Look Like?

Redbacks spiders are quite small, as are the bite marks they inflict. A redback bite will generally be a tiny pinprick puncture wound, or possibly two tiny punctures a millimetre or two apart. In some cases, the bite marks will not be clearly apparent, and the wound might simply appear as an aggravated sore. The bite location will generally be surrounded by an area of red, inflamed skin spreading out from the wound in a rough circle. The area will often show swelling and will generally be quite painful.

It’s common to sweat profusely after a redback bite. Within around 30 minutes, the pain and swelling from the bite will often have spread throughout the body. And after an hour or so, headaches, nausea and vomiting are also typical symptoms.

Redback Spider Symptoms

Redback Spider Bite Symptoms:

  • Pain around the bite area that can become severe
  • Swelling and redness around the bite
  • Sweating, sometimes profusely
  • Nausea and vomiting
  • Headaches
  • Muscle weakness or stiffness
  • Abdominal pain or cramping
  • Difficulty breathing
  • High blood pressure
  • Fast or irregular heartbeat
  • Anxiety or agitation
  • Localised rash or itching

What To Do If Bitten By A Redback Spider

  • Remain calm
  • Apply ice or a cold pack
  • Seek medical assistance
  • Avoid applying pressure or restricting blood flow
  • Find and keep the spider
Redback spider bite first aid

The first thing to do is to remain calm – an estimated 10,000 people each year are bitten by redback spiders, with only one person dying from it in the last 70 years. Apply ice or a cold pack to the area to minimise the pain and control the swelling. At that point, you should seek medical assistance. Hospitalisation is not always necessary, but it’s wise to get help.

Avoid anything that applies pressure to the area or cuts blood flow, such as a tourniquet or a bandage with pressure applied. Redback venom spreads very slowly, and applying pressure or restricting blood flow might just worsen the pain.

If possible, you should find and keep the spider that caused the bite so professionals can identify it (in case antivenom is needed). It doesn’t have to be alive – so long as there’s enough left to identify the species. Just be careful not to get bitten again – multiple redback bites can be more life-threatening.

Red Back Spider Web

Redback spiders are recognised for their unique webs that have an irregular shape and are constructed using powerful, adhesive strands. These spiders build their webs in protected, arid regions like under rocks, logs, and outdoor furniture. 

The silk used to form the webs is remarkably durable, which allows the spider to catch prey and shield itself from predators. Typically, the redback spider suspends itself upside down in its web, waiting for prey to become ensnared. While the spider’s webs can be fascinating to observe, it’s crucial to be cautious around these creatures since their venomous bites can be incredibly harmful to humans.

Spider Bites And Anaphylaxis 

Anaphylaxis, a severe allergic reaction, can occur in certain individuals who have been bitten by a spider. This condition has the potential to be life-threatening, with a rapid onset that can lead to fatality within as little as 15 minutes.

Signs of Anaphylaxis include:

  • Difficulty breathing or shortness of breath
  • Swelling of the face, lips, tongue, or throat
  • Rapid heartbeat or palpitations
  • Dizziness or lightheadedness
  • Confusion or disorientation
  • Hives or widespread itching
  • Nausea, vomiting, or abdominal pain
  • Weakness or feeling faint
  • Loss of consciousness

Spider bites can cause various symptoms, ranging from mild irritation to severe medical emergencies. In rare instances, individuals may encounter anaphylaxis, an intense allergic reaction that can be life-threatening. If you suspect that you or someone else is experiencing anaphylaxis after a spider bite, it is crucial to seek immediate medical assistance.

If any of the following symptoms are observed, it is important to promptly dial emergency services (Triple Zero, 000), refer to the anaphylaxis treatment guideline of the Australian Resuscitation Council (ARC), and adhere to the DRSABCD protocol while preparing to administer CPR.

Spider Bites and Anaphylaxis

Being Prepared

Being prepared for a spider bite emergency is crucial, especially if you live in an area where venomous spiders like the redback spider are common. While it’s important to take preventive measures like keeping your living areas clean and clutter-free, it’s also essential to know how to respond in case of a spider bite.

Investing a day in a certified first aid training course can equip you with the necessary skills and knowledge to recognise the symptoms of different types of spider bites and provide appropriate first aid. A well-designed first aid training course can cover a broad range of topics, including wound management, burns, allergic reactions, choking, and cardiac arrest, among others.

During the training, you’ll learn how to identify the symptoms of a redback spider bite, which can include pain, swelling, sweating, nausea, and muscle weakness. You’ll also learn how to administer first aid to the victim, such as immobilising the affected limb, applying a compression bandage, and seeking medical attention promptly.

In addition to providing hands-on training, a first aid course or first aid certificate online can also help you build your confidence and develop a calm and composed approach to emergency situations. This can be invaluable when dealing with a spider bite emergency or any other medical emergency.

Male Redback Spider

The male redback spider is a small and relatively harmless arachnid that is commonly found in Australia. Despite its small size, the male redback spider is a fascinating creature with unique physical characteristics and behaviours.

Physically, male redback spiders are much smaller than their female counterparts, with a male’s abdomen length of around 3-4 mm, compared to the female’s 10mm. They have a distinctive red or orange stripe on their back, which contrasts with their black body. The male’s legs are also relatively longer than the female’s, and they have a more slender body shape.

One of the most interesting behaviours of male redback spiders is their approach to mating. Unlike many other spider species, the male redback spider does not simply approach the female and mate with her. Instead, he performs a series of complex courtship rituals that involve vibrating his body and tapping on the female’s web to signal his presence. He must be careful during the approach, as female redback spiders are known to be cannibalistic and may attack and kill the male if he fails to impress her with his courtship.

Male redback spiders have a relatively short lifespan, typically living for only a few months after reaching maturity. During this time, they will mate with as many females as possible before they die. However, mating is not without its risks. In some cases, the male may be killed and eaten by the female after mating, especially if she is hungry or feels threatened.

Female Redback Spider

The female redback spider is a small and venomous arachnid that is native to Australia. It is known for its distinctive appearance, which includes a black body with a red or orange stripe on its back. The female redback spider is one of the most dangerous spiders in Australia, and its venom can cause serious health problems or even death in humans.

Physically, the female redback spider is larger than the male, with a body length of around 10mm. They have a round, bulbous abdomen, which is the most distinctive feature of their appearance. The abdomen is usually black, with a red or orange stripe on the upper side, and sometimes with additional white or yellow markings.

One of the most fascinating aspects of the female redback spider is their reproductive behaviour. They are known for their sexual cannibalism, where the female will sometimes kill and eat the male after mating. This is believed to be a way for the female to obtain the nutrients she needs to produce eggs. In some cases, the male may be able to escape after mating without being eaten.

Female redback spiders are also known for their intricate web-building abilities. They typically build their webs in dark, sheltered areas, such as under rocks or logs, or in crevices and corners. Their webs are made of strong, sticky silk, and they use them to catch insects and other prey.

The venom of the female redback spider is highly toxic to humans, and can cause symptoms such as pain, sweating, muscle weakness, and nausea. In rare cases, it can be fatal. However, bites from female redback spiders are relatively rare, as they are generally shy and will only bite in self-defence if they feel threatened.

Male VS Female Redback Spider

The main differences between male and female redback spiders are their physical appearance, behaviour, and venom toxicity.

  • Physical Appearance: Female redback spiders are larger than males, with a body length of around 10mm, while males are only about 3-4mm long. The female’s abdomen is also more bulbous and round, with a distinctive red or orange stripe on the upper side, whereas the male has a slimmer, more elongated body and a less prominent stripe.
  • Behaviour: Male and female redback spiders have different mating behaviours. Males perform a complex courtship ritual that involves tapping and vibrating their bodies to signal their presence to the female. If the male successfully impresses the female, they will mate, and the male will typically leave soon after. However, the female is known for her sexual cannibalism behaviour, where she may kill and eat the male after mating.
  • Venom Toxicity: The venom of female redback spiders is much more toxic than that of males. The female’s venom contains a potent neurotoxin that can cause serious health problems or even death in humans. In contrast, male redback spiders’ venom is much less toxic and is not considered to be a significant threat to human health.

The main differences between male and female redback spiders are their physical appearance, behaviour, and venom toxicity. While male redback spiders may be less dangerous than females, both sexes are important components of Australia’s ecosystem and play a vital role in controlling insect populations.

What Do Redback Spiders Eat?

Redback spiders are carnivorous and primarily feed on insects, such as flies, mosquitoes, grasshoppers, and beetles. They use their strong, sticky webs to trap their prey, which they then immobilise with their venomous bite. Once the prey is subdued, the redback spider will wrap it up in silk and consume it at their leisure.

While insects make up the majority of a redback spider’s diet, they have been known to occasionally feed on other small arthropods, such as other spiders or scorpions. In some cases, female redback spiders have even been observed feeding on male redback spiders after mating. The redback spider is an important predator in Australia’s ecosystem, helping to control insect populations and maintain the balance of the food chain.


Redback spiders have several natural predators that help to control their populations. These include:

  • Praying Mantises: Praying mantises are known to prey on redback spiders, as well as other types of spiders. They use their sharp forelegs to grab and hold onto their prey, before consuming them.
  • Birds: Several bird species, such as butcherbirds and currawongs, are known to eat redback spiders. They use their sharp beaks to pick the spiders off their webs or other surfaces.
  • Wasps: Some species of wasps are known to parasitize redback spider eggs, by laying their eggs inside the egg sac. The wasp larvae then feed on the spider eggs, effectively reducing the number of redback spiders that hatch.
  • Other Spiders: Some larger spider species, such as huntsman spiders, Daddy-long-legs and White Tail Spiders are known to feed on redback spiders. They use their speed and agility to overpower the redback and consume them.

How Poisonous Is A Redback Spider?

The Redback Spider or Latrodectus hasselti, is one of the most venomous spiders found in Australia. Its venom contains a potent neurotoxin that can cause severe symptoms in humans, including pain, muscle weakness, nausea, vomiting, sweating, and increased heart rate.

While bites from a Redback Spider can be very painful, they are rarely fatal, and deaths are extremely rare. In most cases, the symptoms of a Redback Spider bite can be treated with antivenom, pain relief medication, and supportive care.

Do Redback Spiders Go Inside?

Redback spiders are frequently seen in outdoor areas like gardens, sheds, garages, and outdoor furniture. However, they are also capable of invading homes and other structures. Redback spiders tend to prefer building their webs in dark, quiet areas such as cupboards, closets, and basements. During hot and dry weather, these spiders are more likely to infiltrate buildings in search of cooler temperatures and moisture. They may also enter homes seeking prey, like other insects that are attracted to indoor lights. To prevent redback spiders from gaining entry into your home, it’s essential to take preventative measures such as sealing gaps and cracks in doors and windows, using screens on windows and doors, and keeping outdoor items like shoes and toys in tightly sealed containers. If a redback spider is found inside your house, it’s best to seek the assistance of a professional pest control service to handle the situation safely.

Redback Bite And Dogs

Redback spider bites can be dangerous to dogs, especially if they are left untreated. Dogs are curious animals and may accidentally come into contact with redback spiders, which can lead to a bite. 

The symptoms of a redback spider bite in dogs include pain, swelling, and redness around the bite area, vomiting, panting, and lethargy. If you suspect that your dog has been bitten by a redback spider, it is important to seek veterinary attention immediately. Treatment may include the administration of antivenom, pain relief medication, and supportive care to manage any complications that may arise. 

By being vigilant and keeping your dog away from areas where redback spiders are likely to be found, you can help to prevent potential bites and keep your furry friend safe.

Other Australian Spiders

  • Sydney funnel-web spider (Atrax robustus)
  • Mouse spider (Missulena spp.)
  • White taile spider (Lampona cylindrata)
  • Funnel-web spiders (Hadronyche spp.)
  • Trapdoor spider (Genus Idiommata)
  • Wolf spider (Lycosa spp.)
  • Huntsman spider (Heteropoda spp.)
  • Black house spider (Badumna spp.)
  • Brown recluse spider (Loxosceles reclusa) – Although this spider is not native to Australia, it has been occasionally reported in imported goods and can potentially be found in the country.

It’s important to note that although these Common Australian spiders are considered dangerous, most are not aggressive and will only bite in self-defence. However, if you encounter any of these spiders, it’s best to avoid them and seek professional help if you suspect you’ve been bitten.

Can You Survive A Redback Bite Without Antivenom?

Redback spider bites are frequent but usually not fatal, even without medical treatment. The symptoms can last from several hours to a few days and include intense pain. The initial bite may cause only mild discomfort or irritation and sometimes goes unnoticed.

What Kills Redback Spiders?

Several factors can contribute to the death of redback spiders. Predators such as birds, lizards, and wasps may prey on redback spiders. Additionally, parasitic wasps and flies may lay their eggs on the spiders, leading to their death. Insecticides can also be used to kill redback spiders, but it is essential to handle these chemicals carefully and follow all safety precautions to avoid harming other animals or people. Lastly, natural environmental factors, such as extreme temperatures, drought, and flooding, can also impact the survival of redback spiders.

Is A Black Widow Spider The Same As A Redback?

The infamous Black Widow Spider (Latrodectus sp) found in the United States is a near relative of the Redback Spider, distinguishable only by the absence of a red dorsal stripe. Additional Latrodectus species can be found in various regions worldwide, including Africa, Europe, New Zealand (as the Katipo), the Pacific Islands, and both North and South America.

What Is The Deadliest Spider In The World?

Regarded as one of the most hazardous arachnids, the funnel web spider hails from Australia and is known for its venomous bite. The spider’s venom contains an alarming 40 different toxic proteins, which contribute to its reputation as a highly dangerous species.

How Many Types Of Spiders Are Found In Australia?

Australia is home to a vast array of spider species, estimated to number around 10,000. However, only 2,700 of these species have been formally described, belonging to 500 genera and 78 families.

The content on this website offers general insights regarding health conditions and potential treatments. It is not intended as, and should not be construed as, medical advice. If you are facing a medical emergency, dial 000 immediately and follow the guidance provided.

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