Redback spider fact sheet | Field of Mars EEC

What are redback spiders?

A redback spider is a small Australian spider with a venomous bite. The female is the spider most people recognise. She usually has a round black body with a red or orange stripe on top of her abdomen and a red or orange hourglass-shaped mark underneath.

Redback spiders are part of the widow spider group. They build messy, tangled webs in dry, sheltered places. They are found across Australia and are especially common in disturbed places near people, such as sheds, fences, garden edges, outdoor furniture, stored materials and sheltered corners.

Redback spiders are important predators, but they should not be touched. They usually bite only when pressed, trapped or handled. Students should observe spiders carefully from a safe distance and tell an adult if a redback spider is found in a place where people may accidentally touch it.

A redback spider.

Female redback spiders are easy to recognise by the red or orange stripe on the upper abdomen.

Where do redback spiders live?

Redback spiders are found throughout Australia, including NSW. They can live in many places as long as there is enough food, warmth and a dry, sheltered web site. In Sydney, they may be found around buildings, fences, sheds, outdoor furniture, garden materials, rock edges, logs and stored objects.

A redback spider’s web is usually messy and tangled. It has a sheltered retreat area and sticky catching threads that run down to nearby surfaces or the ground. Redback spiders often stay close to their web, so people should be careful when lifting objects that have been sitting undisturbed outside.

Redback spiders often build webs in dry, sheltered corners around homes, gardens and outdoor structures.

What do redback spiders eat?

Redback spiders are predators. They mostly eat insects and other invertebrates that become caught in the sticky lines of their web. Their prey can include flies, beetles, crickets, cockroaches, moths, other spiders and other small animals.

Large female redback spiders can sometimes catch bigger prey, including small lizards, if the animal becomes trapped in the web. The spider bites the prey, wraps it in silk and feeds by sucking up liquefied body tissues.

Redback spiders mostly eat insects and other invertebrates, but large females can sometimes trap small vertebrates.

What is the life cycle of redback spiders?

Female redback spiders make round silk egg sacs and hang them in the web. A female can produce several egg sacs after mating. Each sac may contain many eggs, and the young spiderlings hatch after several weeks.

Newly hatched spiderlings are tiny. Some may eat unhatched eggs or other spiderlings. Young redback spiders can disperse by ballooning, where silk threads catch the air and carry them away to new sheltered places. Females live much longer than males and can survive for several years in suitable conditions.

Female redback spiders make round egg sacs and keep them in the web.

What adaptations do redback spiders have to help them survive?

Redback spiders have strong silk that helps them make tangled webs. Sticky catching threads can trap insects and other small animals that walk or fly into the web. The spider can sense movement through the silk and move from its retreat to capture prey.

Their red and orange markings may help people and other animals recognise them as dangerous. Redback spiders also use sheltered web sites to avoid weather, predators and disturbance. If threatened, they may drop lower in the web or stay still rather than chase or attack.

Redback webs include sticky catching threads and sheltered spaces where the spider can hide.

Why are redback spiders important?

Redback spiders help control populations of insects and other small animals. Like other spiders, they are predators in food webs and help move energy through ecosystems when they eat prey and when they are eaten by other animals.

Redback spiders are also part of Australia’s biodiversity. They can be dangerous to people if handled or accidentally pressed against skin, but they are not pests in every situation. The safest approach is to leave spiders alone, reduce accidental contact and remove webs carefully only when they are in places people use.

Redback spiderlings are part of food webs from the time they hatch.

How can you stay safe around redback spiders?

Redback spiders should be watched from a safe distance and never touched. Before sitting on outdoor furniture or moving objects that have been outside for a long time, check dry, sheltered places such as under seats, around pot plants, in sheds, behind stored materials and near fence lines. Wear gloves when gardening or moving rocks, logs, pots, bricks or outdoor equipment.

If you find a redback spider in a place where someone might accidentally touch it, move away and tell an adult. An adult can decide whether the web needs to be removed or whether the spider can be left alone. Do not poke the web, try to catch the spider or put your hands into places you cannot see.

If someone may have been bitten, tell an adult immediately. Wash the area and keep it clean, do not apply a pressure bandage, and call the Poisons Information Centre on 13 11 26 for advice. Visit the nearest hospital if symptoms are severe, and call Triple Zero (000) if the person is unconscious, not breathing or has a serious allergic reaction.

Redback spiders can hide on outdoor equipment, so check carefully before placing hands in sheltered spaces.

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