Redback spiders are thought to have made the journey to the eastern states from Western Australia and South Australia. The shelter provided by buildings, outhouses, farm machinery, patio furniture and all the other trappings of civilisation have made them very comfortable around humans, although that feeling is definitely not reciprocated. They have hitched rides in items bound for overseas in shipping containers, and are now found in Osaka, Japan, New Caledonia, New Zealand and parts of Europe.
The redback is a webbing spider as opposed to a crawling or hunting spider. The female is the largest at 12-15mm while the male is much smaller at 3-4mm and is rarely seen. The redback has a large bulbous abdomen with the famous red or orange stripe appearing on the top. The legs are long and thin, tapering at the ends. The male is a different colour to the female, usually with a white abdomen with 4 black bars on each side.
Redbacks breed throughout the year but are most active in summer. They can produce several egg layings in a season if the conditions are right. They can produce up to 7 spherical cocoons containing 50 to 200 eggs in the late summer.
In their natural environment they inhabit hollow logs and tree roots, hide under stones and bark with some part of the web always touching the ground. Around human habitation they typically are found in garages and garden sheds, around swimming pools, under patio furniture and barbeques, and in machinery that has lain idle.
Their webs are fine and often tangled with leaf litter and small twigs, and hold the spherical, cream coloured cocoons which contain their eggs. These are usually found at the top of a type of funnel with the female, in a retreat of dead leaves bound with silk webbing and sheltered from the elements
The main prey of redback spiders are insects, mice, small birds, lizards and other spiders. The bite releases a venom containing latrotoxin which is effective on most animals.
Detrimental Effects to Humans and Property
The redback spider webs are untidy and like other types of webs, look unsightly in and around the home or commercial premises. However, the most disturbing feature of a redback spider is their bite which has been known to be fatal. People who have experienced this report just a mild sting initially, followed within five minutes or so by a burning sensation and intense local pain around the bite.
As the symptoms develop the victim can experience muscular weakness, sweating, paralysis, tremors and lack of coordination. Nausea, vomiting, dizziness and fainting have also been reported. Only the female is known to bite, and the results can be quite variable. The spider has full control over the amount of venom injected into the victim, and can produce a dry bite i.e. a defensive bite free of venom.
No chances should ever be taken with the bite of a redback spider as there is no way of knowing if the spider has injected venom. Medical attention must be sought urgently. Fatalities in Australia are not common since the introduction of an antivenin in 1956. However, the bite will make the victim very ill even after receiving the antivenin, especially if they are very young children or the elderly.
Wearing gloves and closed in shoes while gardening or working around the yard is the best personal protection against redback bites. Fortunately the redback is not an aggressive spider and will retreat or play dead if under threat. However, hundreds of people still get bitten each year in Australia and require medical attention.
The best solution is to call on the professionals. The team at Bob Gunn Termite Solutions are trained, experienced and licenced to advise on the best method for eradicating redback spiders and will offer a solution that suits each individual circumstance.