SPIDERS IN GENERAL
Spiders belong to the order Arachnida, along with scorpions, harvestmen, mites and a number of other less well known animals.
Spiders differ from insects in lacking wings, and in having two body sections, instead of three, and four pairs of legs, instead of three. Most spiders have eight eyes, although some have less. Although some adult spiders are only 0.5mm long, the giant theraphosid spiders of South America can have a leg spread of 28cm and weigh 120 grams.
Australia has a large and varied spider fauna, with many species yet to be identified and named. The spiders described here can be found in and around around houses in the ACT and eastern NSW. The accurate identification of spiders requires specialized knowledge and equipment and this booklet is meant only as a general guide.
All spiders have a pair of fangs or chelicerae near the mouth that in most families are connected to venom glands.
The fangs are used to inject venom and digestive juices into prey. The prey’s tissues are dissolved in this way and the resulting ‘soup’ is sucked into the spider’s tiny mouth.
The spider’s abdomen is mostly filled with a network of tubes in which food is stored and digested. The elasticity of the abdomen means that large amounts of food can be eaten and stored at a time, allowing spiders to withstand long periods of starvation.
Silk plays an important role in all aspects of a spider’s life and it is produced from special glands at the tip of the abdomen. While some spiders use silk mainly for protecting their eggs and for orientating, others also build elaborate snares and webs in which to capture prey. Only a few species of spiders are capable of delivering a bite which seriously effects humans. The vast majority are harmless and play a vital role in keeping insect numbers in check. If you take time to observe spiders in your house or garden you will discover them to be interesting and fascinating animals.
CANBERRA'S GARDEN ORB-WEAVER
Eriophora and Araneus species
Eriophora are large, humped spiders, variable in colour and with a leafshaped pattern on the back. They build large orb webs between bushes and prey on flying insects, particularly moths. The many smaller Araneus species are similar in shape and habit to Eriophora, and some are brightly coloured with metallic hues. Orb spiders build intricate webs at twilight and later destroy and devour them in the early hours of the morning, leaving guide lines to mark their position. During the day orb spiders hide in crevices or vegetation, concealed by their cryptic colouration. Many species have the ability to change their colour to blend with the surface in which they are resting. Orb spiders are not aggressive and bites are rare.
CANBERRA'S BLACK HOUSE SPIDER
These black, grey speckled spiders build dense ‘furry’ grey webs in the corners of windows and under eaves. There are several funnels leading to a retreat, from which the spider runs forth to capture prey. The dense appearance of the web is due to the special type of complex silk the spider produces, and its tendency to gather dust. Black house spiders can bite painfully if provoked, but would much rather catch insects. Due to their black colour and funnel-shaped webs these spiders are often mistaken for Funnelweb spiders. Although the untidy appearance of the webs can be a nuisance, Black House spiders are thought to help keep Redback spider numbers in check.
CANBERRA'S REDBACK SPIDER
Female redback spiders are spherical black spiders with thin legs and a distinctive red stripe on the back of the abdomen. They build tough, untidy webs in the shade, with a hidden retreat. The male redback is small, harmless and easily overlooked. Redbacks are common around ACT houses and can be found in abundance during the warmer months. Clearing away the webs and spherical egg sacs helps to keep their numbers under control. Steatoda is a common spider which is often mistaken for redbacks, but it lacks the characteristic red stripe. Although their venom is very toxic, redbacks are not aggressive and usually only bite when handled. Medical attention should be sought after all bites. Contrary to popular belief Redback spiders are not native to Australia and probably arrived from Asia in the 1880s. Redbacks in Canberra are currently being replaced by another accidental import, the less dangerous Brown Widow spider Latrodectus geometricus.
CANBERRA'S WOLF SPIDER
Numerous genera species
Australia has over 200 species of Wolf spiders. Wolf spiders have good eyesight and run down their prey. Often large and aggressive, they build burrows in the soil. Although the bite of local species is painful, it is not known to be dangerous. Female Wolf spiders drag their egg-sacs around attached to their spinnerets, and allow newly hatched young to ride on their backs. Wolf spiders commonly come into houses after rain and are often mistaken for Funnelweb spiders. The Italian folk dance, the tarantella, is named after a mediterranean wolf spider, the tarantula, whose bite in medieval times was believed to cause dancing and licentious behaviour.
CANBERRA'S HUNTSMAN SPIDER
Isopoda, Delena and Neosparassus species
These large, agile spiders are common in houses. In nature they hide in narrow crevices, venturing out at night to hunt insects and small vertebrates. While Isopoda and Delena have flattened bodies for hiding under bark, Olios is more rounded and lives among foliage. Huntsman spiders are often found near outside lights, preying on moths. Delena is an unusual spider in that it often forms ‘colonies’ of up to 300 individuals under the bark of trees. They seem to live together harmoniously without the typical cannibalism of spiders. Although the bite of Huntsman spiders can be painful they are not dangerous.
CANBERRA'S FUNNEL WEB SPIDER
Atrax and Hadronyche species
Funnelwebs are large, shiny black spiders that dig burrows in the ground or in rotting wood, usually in undisturbed bushland. The burrow, which does not resemble a funnel, is lined with silk and often has several flattened web tubes at the entrance. Funnelwebs are common in eastern and southern Australia and the 30 or more species are all thought to be dangerous. When disturbed Funnelwebs raise the front part of their body off the ground and strike repeatedly with their long, downward pointing fangs. Males leave their burrows on summer nights and wander in search of females. All fatal bites have been from males, which have the most toxic venom. The bite treatment is the same as for snake bite, and medical attention should be sought immediately. Funnelwebs are native to the ACT and are sometimes brought into houses in firewood. Although not yet common in the suburbs, the number of Funnelwebs found near houses in Canberra seems to be increasing.
CANBERRA'S WHITE-TAILED SPIDER
These dark, elongated, spiders cruise around the walls of houses during summer. They seem to feed mainly on other spiders, particularly the black house spider. In nature Lampona lives under the bark of trees, while in houses it often shelters amongst bed clothes and pillows. Recent reports in the Press that the bite of Whitetailed spiders can cause severe ulcers have no factual basis.
CANBERRA'S JUMPING SPIDER
Numerous genera species
These small, square fronted spiders have the central pair of eyes in the front row greatly enlarged and they hunt their prey by sight. Many of the species that enter houses are bark and foliage dwellers, and they stalk their prey around the walls and ceiling. If you approach a Jumping spider slowly with your finger it will turn its body so as to follow the movement with its eyes. None of the local Jumping spiders are known to be dangerous to humans.