Redback Spider Bite

Spider with Red Stripe
Redback Spiders are found across Australia in warm, sheltered sites. They are known for their distinct red stripe and venomous bite.

Redback Spiders are considered native to Australia and are found across the country. They prefer to build their webs in dry, sheltered sites, and so they are common in close proximity to human habitation. Bites from a female Redback have been known to cause serious illness and even death.

What do Redback Spiders Look Like?

Female Redback Spiders are typically black in colour, though they can sometimes be brown. Their most distinct feature is a red or orange stripe on the top of their abdomen.

Male Redback Spiders, meanwhile, are usually light brown in colour with white or yellow markings on their abdomen, as opposed to red or orange ones.

Both male and female Redback Spiders have an hourglass shaped marking on the underside of their abdomen, though the male's is much more pale than the female's. Male Redback Spiders are also much smaller than their female counterparts, and they only grow to a modest 5mm compared to the female's 1 cm.

Redback Spider on deck
Female Redback Spiders are about the size of a pea and have slender legs. They are typically black in colour with a red or orange stripe on their backside.

Where do Redback Spiders Live?

Redback Spiders can be found across Australia wherever there is sufficient food, shelter, and warmth.

Due to their predilection for dry, sheltered sites, Redback Spiders tend to build their nests, which typically comprise a funnel-like upper retreat area surrounded by sticky catching threads, close to human habitation in sheds, toilets, and under rocks and junk piles.

How Dangerous are Redback Spiders?

Redback Spiders are generally retiring creatures and only bite in defence. Likewise, they usually stick to their own webs, though females have been known to steal prey from other webs.

To this end, female Redback Spiders tend to be more aggressive than their male counterparts. They are also the only ones capable of harming humans, as the male's fangs are too small to penetrate human skin. As such, it is unlikely for a human to be bitten by a Redback Spider unless one of their body parts, such as a hand, comes into direct contact with a web or a female.

The venom from a Redback Spider acts directly on the nerves and results in the release and subsequent depletion of neurotransmitters. More than 250 victims of Redback Spider bites receive antivenom each year. It is thought that an additional number of envenomations go unreported each year due to the mildness of the symptoms. Redback Spider bites can cause serious illness and have resulted in deaths, though no deaths have been reported in Australia since 1955, a year before antivenom was introduced.

A redback spider, Latrodectus hasseltii, of the family Theridiidae. ©CSIRO
Redback Spider bites can cause localised pain around the bite site and, in more severe cases, abdominal pain, shallow breathing, and loss of coordination.

What are the Symptoms of Redback Spider Bites?

Redback Spider bites are characterised by intense localised pain, redness, and swelling around the bite site. Other common symptoms of a Redback Spider bite include:

  • Sweating.
  • Nausea, vomiting, and abdominal pain.
  • Loss of coordination.
  • Tenderness in the armpit or groin of the affected limb.
  • Rapid, shallow breathing.

How do you Treat a Redback Spider Bite?

  • Reassure the casualty and keep them under constant observation.
  • Apply a cold compress to the bite site for periods of up to 20 minutes to lessen the pain.
  • If the casualty is a young child (under 8 years), a pregnant woman, or if they exhibit any signs of deterioration, call Triple Zero (000) for an ambulance.
  • DO NOT use the Pressure Immobilisation Technique, as the venom moves slowly and this will just worsen the pain.

The bite site is likely to remain red and itchy for a few days after the bite occurs. If symptoms are still present after 7 days, revisit your doctor.

More information about how to identify and treat spider bites can be found in our resource library.

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