The female Red-back Spider is easily recognised because of her distinctive body colours and shape. The body has a characteristically pea-shaped abdomen and the legs are long and slender. The upper side of the abdomen usually has a broad red stripe, while the underneath always has an hourglass-shaped red mark. Juvenile females have white markings on the abdomen. The female’s body is about 10 mm long, excluding the legs.
A female Red-back Spider (black and white illustration)Illustrator: Graham Milledge / Source: Museum Victoria
The male Red-back Spider is much smaller than the female – only about 4 mm – and it is rarely seen. The body is light brown, with no red markings, but there are white marks on the upperside of the abdomen and a pale hourglass mark underneath.
The Red-back Spider makes a web to catch its prey. It consists of a tangled array of sticky catching lines attached to the surroundings.
A female Red-back Spider at its webPhotographer: Graham Milledge. Source: Museum Victoria
This spider is commonly found outdoors around human habitation in such places as rubbish, litter, old tins and containers, under and on steps of the veranda, and on, or under the seats of outdoor toilets. Storage stacks and disused furniture will encourage the breeding of this spider. In nature, it occurs under logs, bark, sides of rocks, etc. As the spider rarely leaves its web, humans are not likely to be bitten unless some part of the body (e.g. the hand) is put into the web.
Always check before moving items that have been stored outdoors for some time. Wear gloves when cleaning up rubbish areas.
The female produces up to 10 pale yellow egg sacs, each with approximately 250 eggs. Females may live for two to three years, and males for about 90 days.
The bite is highly venomous. It is characterised by intense localised pain around the bite site. Other symptoms may include sweating, muscular weakness, loss of coordination and, in severe cases nausea, vomiting, convulsions, etc. Antivenom is available.
The following description of the signs and symptoms of envenomation is quoted with permission from Australian Animal Toxins, by Struan Sutherland (Oxford University Press, 1983).
‘The normal sequence of events after a bite is as follows. A sharp pin-pricking pain is almost invariable. Usually the bite site becomes hot. Erythema and oedema develop rapidly. Localized sweating often occurs. The swelling is generally limited to an area of several centimetres in radius from the bite site; occasionally it is extreme. Approximately five minutes after the bite, intense local pain commences and increases in severity and distribution. In most cases, pain is the predominant symptom; the patient is sometimes distraught and even hysterical because of its intensity. Movement of the affected limb often significantly increases the pain. About thirty minutes after the bite, pain and swelling are often experienced in the regional lymph nodes. If abdominal pain occurs, it is worse when the lower extremities or genitals were bitten, probably due to lymph node involvement. Sometimes severe pain develops in parts remote from the bite site, for example, in an opposite limb or the opposite side of the trunk.
Uncommon, even bizarre, signs and symptoms have developed in some cases. These include tetanic spasms, tingling in the teeth, swelling of the tongue, bite site infection, convulsions, excessive thirst, severe diarrhoea, anaphylactic reaction to the venom, blotchy rash on face, haemoptysis, dyspnoea, dysuria, severe trismus, persistent anorexia, periorbital oedema and/or conjunctivas. Patchy areas of what was described as “bizarre sweating” are not uncommon.’
Brunnet, B. 1994. The Silken Web – A Natural History of Australian Spiders. Reed Books: Melbourne.
Lindsey, T. 1998. Spiders of Australia. New Holland Publishers: Sydney.
Walker, K. L., Yen, A. L. and Milledge, G. A. 2003. Spiders and Scorpions commonly found in Victoria. Royal Society of Victoria: Melbourne.
Hi. Currently, the Live Exhibits team don’t need any Red-Backed Spiders. Perhaps try contacting the Australian Venom Research Unit at Melbourne University http://www.avru.org/index.html
We love receiving comments, but can’t always respond.
Hi All, we have been getting a few comments and questions as to why the Red-back spider shown on this infosheet has no red on its abdomen. The reason is that the first image shown is a scientific illustration and is done in black and white.
Hi Jenn, Museum Victoria's expertise lies more in spiders found in south-eastern Australia. I'm not sure if you are contacting us from Ontario, Canada or Ontario, New Zealand. You could try the Natural History Museum in your country who should have knowledge of local spiders. Or if you can safely obtain an image of the spider please feel free to send it to email@example.com and we will see if we know it.
Hi Karina, probably the best thing to do is to contact your local Natural History Museum in North Carolina and see if they can provide a positive identification for you. Spiders have no interest in people and will not come looking to bite them for no reason. Bites usually occur when people accidentally put their hands in the webs or stand on them.
Hi Carol. Our Victorian Spiders website features a spider gallery and spider search to help identify species local to Victoria. If this doesn't confirm the identification, you can send a specimen or clear photograph to us and we'll attempt to identify the spider for you. Hope this helps!
Hi Heather, thanks for enquiry, unfortunately the entomologist needs an image in order to identify the spider you saw at home. Have a look at the Victorian Spiders website, you may find that you are able to identify the spider yourself
Unfortunately without an image it is impossible to provide an accurate ID, however you could try browsing the Spiders of Australia website to try to identify it yourself. A red-back can have the red colouring on both its back and underside, but it usually has a pea shaped body.
If you are happy to drop the spider off we would be happy to recieve it. Bring it down to the Discovery Centre on the lower ground floor of the Melbourne Museum - open Tues-Sat 10am-4:30pm and we will pass it on to our Live Exhibitis team.
Saw one last night on our verandah. Probably coming out of the rain. I have seen them before but this one was at least 85 cms. long which made me wonder because...
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