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. Their tough, untidy webs are usually near the ground with the spider hiding in a shelter in a corner, often guarding her round woolly egg sacs. Immature females are smaller, usually brown with whitish markings. Males are rarely seen; they are small and brown with red and white markings.
Throughout Australia, in drier habitats and built-up areas. Often common in dry places around buildings, outdoor furniture, machinery and stacked materials. In the bush, they nest under logs and rocks. Evidence suggests that Redbacks are not native to Australia.
Redbacks 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. 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 Redbacks turn up in new places.
Redback spiders are not aggressive, but 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 and fever.
Anyone bitten by a redback spider should seek medical attention. Do not bandage the bite - apply iced water and take simple painkillers. An antivenom is available and very effective.
Learn to recognise their webs and the kinds of places they live. In places where they might be a hazard, destroy the spiders as you find them. Poke a stick into the retreat to squash or remove the spider, and destroy any egg sacs. Take care not to be bitten. Fumigation has only temporary effects on Redback numbers and kills natural enemies.