Australian redback spider
Latrodectus hasselti
Photo courtesy of: The University of Southern Queensland
This species is established in parts of New Zealand.
Description
The redback spider Latrodectus hasselti is native to Australia. It is easily recognisable by its black body (occasionally brownish) with prominent red/orange stripe on its abdomen. The red/orange strip on its abdomen distinguishes it from the false katipo spider. Redback spider females measure about 1 cm in body length while the male is smaller being only 3 to 4 mm in body length.
Webs consist of a tangled, funnel-like upper retreat area from which vertical, sticky catching threads run to ground attachments. The redback spider favours proximity to human habitation, with webs being built in dry, sheltered sites, such as among rocks, in logs, shrubs, junk-piles, sheds, or toilets. Redback Spiders are less common in winter months.
Impact
The redback spider has venom which is toxic to humans with bites causing severe pain. The larger female spider is responsible for almost all cases of redback spider bites in humans.
If you suspect you have been bitten by a redback spider you need to seek urgent medical attention. If possible clean the wound with antiseptic or warm soapy water and place ice on the bite (not directly on the skin) prior to traveling to the nearest hospital. Do not apply pressure to the wound or consume alcohol after being bitten. Even if you do not immediately experience symptoms beyond the ‘pin prick’ of the bite you should still seek medical advice.
Do not panic, serious reactions are uncommon and unlikely to develop in less than three hours. Hospitals can provide safe and effective treatment.
If it is possible to capture the spider without endangering anybody, do so and take it to the hospital with you. The spider should be approached with caution and fly spray that claims to be effective on spiders used to stun the spider prior to killing it and/or placing it in a sealed jar.
Distribution
The distribution of redback spiders is not fully known but populations exist in central Otago.
Management
Surface sprays applied directly will kill redback spiders. However treatment must be repeated often to deal with spiders which are carried in on the wind. Such insecticides will also affect many non-target species.
An effective way of controlling redbacks is to carry out regular inspections of suitable Redback habitats, searching for spiders and their webs. The spiders may be removed by pushing a stick into the back of the web and twisting the web, spider and any egg sacs around it. If all the webs on a property are removed, new arrivals will quickly become apparent by the presence of new webs.
As redbacks generally make their webs under some form of shelter, they are often not seen. If you live in an area known to have redback spiders, check any potential web sites before putting your hands there. Wear gloves when gardening.
If you are concerned about the presence of redback spiders on your property, contact you local pest controller for assistance.
Resources
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MAF Biosecurity New Zealand
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