'White-tailed spiders' is a term used to describe many species of spiders in the family Lamponidae, found in Australia. There are thought to be around forty species in Australia, and two species are thought to have moved to New Zealand. The two most commonly-found species are Lampona murina and Lampona cylindrata, although the differences between the two species can't generally be observed by the naked eye. Both species were described by Ludwig Koch1 in the 1800s.
White-tailed spiders are reddish-brown or grey. Despite its name, the spider's 'white tail' can often be hard to see. There are faint white spots near the top of the abdomen (usually only visible in juveniles) and a small white tip on the end of the abdomen. Female spiders are larger — they reach around 16-18mm, whereas males reach only 12mm and have smaller abdomens. Their banded legs are often described as 'shiny' or 'glossy'.
White-tailed spiders live both inside and outside. Like most spiders, they generally prefer hiding under things or in nooks and crannies. Outside, they are often found in or around rocks, bark or leaf litter. Indoors, the equivalent is linen or clothing, especially left in piles on the floor. Removing all other spiders (that is, the prey of the white-tailed spiders) and their webs from your house is a good way to decrease your population of white-tailed spiders.
Although female white-tailed spiders spin webs for looking after their eggs, generally the spiders do not reside in webs but move about searching for their prey.
White-tailed spiders appear to be more common in the southern parts of Australia.
Cannibal alert! White-tailed spiders prefer to eat other spiders. This even includes the dangerous redback spiders. They particularly love black house spiders. In fact, it is said that you can tell white-tailed spiders are living in your house when all other spider and cobweb presence disappears!
For white-tailed spider eggs to hatch, the temperature needs to be quite warm, usually above 20°C. This explains why the spiders are often found inside. The eggs are contained within an egg sac, laid by the female. Each egg sac can contain up to about 100 eggs. The female lays and guards the egg from within a temporary web. The eggs take three weeks to hatch.
White-tailed spiders do often bite humans, although usually only when 'provoked'. Unfortunately, such provocation can be as simple as accidentally touching them. Symptoms are not as severe as it was once thought. There had previously been reports of white-tailed spider bites causing ulceration of the skin, known as necrotising arachnidism. A 2003 study published in the Medical Journal of Australia, however, suggested that white-tailed spider bites alone do not seem to be the cause of such bad necrosis. It is thought that the bad ulcers are either caused by another bite mistakenly blamed on the white-tailed spider, or may possibly have been worsened by an infection or allergic reaction.
Most people are actually bitten when they are inside their houses and the spiders tend to disappear quickly afterwards. Few people ever see what is biting them! It is for that reason that a white-tailed spider bite can be hard to diagnose. The symptoms include localised pain, swelling, discolouration and itching. An ice-pack or creams can be used to reduce pain and swelling if necessary. Medical attention is probably not necessary unless the reaction persists or becomes more serious.