Brown recluse spiders are found all over the world, though you are very unlikely to see one roaming about, as they are nocturnal and hunt for food at night.

Though it is not in their nature to engage in a fight, Brown recluse spiders will not hesitate to bite if they feel disturbed or trapped.

For this reason, it is best to steer clear of Brown recluse spiders. Their bites are venomous and have been known to cause necrotic rotting skin and even death, especially in children.

In this article, we’ll be covering everything you need to know about the Brown recluse spider, including what they are, what to do if you are bitten by one, and whether they are dangerous to humans.

What are Brown recluse spiders?

Brown recluse spiders belong to the Sicariidae family. The Sicariidae family contains approximately 160 different spider species, the most renowned members of which are the Brown recluse spider and the six-eyed sand spider.

Brown recluse spiders reach adulthood in the span of one year, and they typically live for two to four years in the wild. Female Brown recluse spiders can produce fertilised eggs throughout their lifetime by mating just one. Likewise, they can produce an estimated 150 spiderlings every year.

What do Brown recluse spiders look like?

Brown recluse spiders have violin-shaped markings on their cephalothorax, which is why they are sometimes called the fiddleback spider or violin spider. These violin markings can in vary in intensity as the spider ages, and older spiders tend to have darker brown violin markings.

However, violin markings cannot be used on their own to determine whether a spider is a Brown recluse. The most reliable way to identify a Brown recluse spider is by studying the eyes – Brown recluse spiders have six eyes instead of eight, and they are arranged in three pairs.

What do Brown recluse spiders eat?

The diet of a Brown Recluse spider is a little different from those of other spiders, and their favourite prey includes silverfish, cockroaches, and crickets. They are also considered running spiders. As such, instead of using webs to capture their prey, Brown recluse spiders hunt them down like wolves, before injecting and subduing them with a deadly venom.

The Brown Recluse spider can survive for up to six months in extreme drought and without any food. If food becomes scarce, especially during the mating season from June to September, Brown Recluse spiders have been known to cannibalise their own kind.

Where are Brown recluse spiders found?

Brown recluse spiders were introduced to Australia, and they can be found across the globe. They love warm climates and are most commonly found in the central and southern parts of the United States.

In the wild, they live under rocks, logs and woodpiles. They have also been known to venture indoors to live alongside humans. They can withstand mercilessly cold winters in unheated basements, as well as blisteringly hot summers in attics. Though Brown recluse spiders hunt at night for insect prey, they spend their days hidden away in dark and secluded areas.

Are Brown recluse spiders aggressive towards humans?

The Brown recluse spider gets its name from its brown colour and shy and passive nature. They go out of their way to avoid humans – in fact, it is common for people to live inside houses or buildings that are overrun with Brown recluse spiders and never get bitten.

Most bites occur when a Brown recluse spider is trapped against human skin – for instance, when a person rolls over in bed or puts on a piece of clothing that contains a Brown recluse spider. Keep in mind, they have tiny fangs that cannot bite through fabric.

Are Brown recluse spiders dangerous to humans?

Brown recluse spiders rarely bite humans. The following symptoms could indicate that you have been bitten by a Brown recluse spider:

• Burning, itching, or redness at the bite site.
• Head and body aches.
• Rash.
• Fever.
• Nausea or vomiting.

A dark blister or ulcer may also form over the wound in the few days or weeks following the bite. In some cases, the ulcer can worsen and become necrotic. Skin necrosis is a condition that causes the cells of the body to die. Though this condition can be fatal, not many deaths have been recorded.

In rare cases, the bite can also cause systemic loxoscelism, a blood clotting disorder that can lead to widespread haemolysis (the destruction of red blood cells), coagulopathy (excessive bleeding or clotting), and death.

First aid for a Brown recluse spider bite

If you are bitten by a Brown recluse spider, consult the following steps:

• 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, follow the basic life support guidelines per DRSABCD and 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.

If symptoms are still present or worsen after 7 days, seek medical attention.

Check out our Resource Library for information on how to identify and treat bites from ten of Australia's most venomous spiders.

Spider bites and anaphylaxis

Some people can have a severe allergic reaction when bitten by a spider. This is called anaphylaxis, a condition that can be fatal in as little as 15 minutes. Symptoms include:

• Tightness of the throat from swelling.
• Difficulty breathing.
• Tongue and facial swelling.
• Hoarse voice or difficulty speaking.
• A wheeze or persistent cough.
• Collapse or falling unconscious.
• Becoming pale or floppy (young children).
• Abdominal pain and vomiting.
• Hives, welts, and body redness.

If the casualty begins exhibiting any of the above symptoms, call Triple Zero (000) for an ambulance, consult the Australian Resuscitation Council's anaphylaxis treatment guideline, and follow DRSABCD and prepare to perform CPR.

Other fun facts about the Brown recluse spider

• The Brown recluse spider can self-amputate one of its legs as a defence mechanism to distract its predator and allow some time to escape. Unfortunately, the spider will not be able to regenerate a new leg, even after moulting.
• Every time it loses one of its legs, the Brown recluse spider changes its gait to compensate for the loss.

Final thoughts

If you would like to learn more about providing first aid in the event of a bite or sting, book a First Aid course with us today.

We also have articles on what to do if you get stung or bitten by snakes, fire ants, and marine life.

And for more details on how to identify and treat bites from some of Australia's deadliest spiders, including White tail spiders, Wolf spiders, Huntsman spiders, and Redback spiders, head to our Resource Library.

Disclaimer: This article is for informational purposes only. It does not constitute, replace, or qualify as any form of first aid training.