Redback spider, Latrodectus hasselti.

A redback spider, Latrodectus hasselti.

Redback spider

The redback spider is one of Australia’s most recognisable species and they are commonly found in habitats ranging from bushland to urban areas.

  • 1 October 2008 | Updated 14 October 2011

Description

Redback spiders, Latrodectus hasselti, are almost too familiar to need description.

Mature female redbacks are jet black spiders with a variable red stripe on the back of their spherical abdomen. Immature females are smaller, usually brown with whitish markings.

Their tough, untidy webs are usually near the ground with the spider hiding in a shelter tucked in a corner, often guarding her round woolly egg sacs.

Male redback spiders are rarely seen. They are small and brown with red and white markings.
 
Redback spiders are found throughout Australia, in drier habitats and built-up areas. They are common in dry places around buildings, outdoor furniture, machinery and stacked materials.

In the bush, redback spiders nest under logs and rocks. There is some evidence to suggest that redbacks are not native to Australia.

Redback spider bites usually occur when part of the body comes in direct contact with the spider or its web.

Life history

Redback spiders feed mainly on ground-living insects that blunder into their webs, but small vertebrates such as lizards and even mice can fall victim.

Also eaten - after mating - are the tiny male redbacks.

A female redback spider can produce eggs for up to two years after a single mating. Eggs are enclosed in 3-5 dirty-white, woolly, spherical egg sacs suspended in the retreat of the web and guarded by the female.

Spiderlings emerge after about 14 days and disperse on the wind as soon as conditions are right. This is how redback spiders turn up in new places or quickly recolonise areas from which they have previously been removed.

Pest status and management

Redback spiders are not aggressive, and rarely leave the web. However caution is advised as their bite is very poisonous and potentially fatal for children or the elderly.

After a bite, the onset of pain may be delayed for five minutes then increase in intensity. Subsequent symptoms vary but have included:

  • nausea
  • vomiting
  • abdominal or generalised pain
  • sweating
  • restlessness
  • palpitations
  • weakness
  • muscle spasm
  • fever.

Anyone bitten by a redback spider should seek medical attention.

Do not bandage the bite but apply iced water and take simple painkillers.

An antivenene is available and very effective.

Manage redback spiders by learning to recognise their webs and the kinds of places they live. Always take care when gardening or moving objects where redback spiders might be hiding.

Fumigation has only temporary effects on redback spider numbers and kills its natural enemies.

CSIRO Entomology is not currently researching redback spiders. This fact sheet is provided for information only.

State museums and Canberra Connect in the ACT will usually provide identification and advice for the general public.

Read more spider fact sheets in Factsheets & Publications.