Editing Redback spider (section)

{{Short description|Species of spider}}
{{Featured article}}
{{Use dmy dates|date=December 2020}}
{{Use Australian English|date=August 2011}}
{{Speciesbox
 | name                = Redback spider
 | taxon               = Latrodectus hasselti
 | image               = Latrodectus hasselti close.jpg
 | image_caption       = Adult female red back spider
 | image2              = Latrodectus hasselti male.png
 | image2_caption      = Adult male (considerably smaller than female)
 | authority           = [[Tord Tamerlan Teodor Thorell|Thorell]], 1870<ref name=WSC_s39048/>
 | synonyms            = {{plainlist}}
* ''Latrodectus hasseltii'' {{small|[[Tamerlan Thorell|Thorell]], 1870}}
* ''Latrodectus scelio'' {{small|[[Tamerlan Thorell|Thorell]], 1870}}
* ''Latrodectus scelio indicus'' {{small|[[Eugène Simon|Simon]], 1897}}
* ''Latrodectus indicus''  {{small|[[Reginald Innes Pocock|Pocock]], 1900}}
* ''Latrodectus hasselti indicus'' {{small|[[Frederick Octavius Pickard-Cambridge|Pickard-Cambridge]], 1902}}
* ''Latrodectus ancorifer'' {{small|[[Friedrich Dahl|Dahl]], 1902}}
* ''Latrodectus hasselti aruensis'' {{small|[[Embrik Strand|Strand]], 1911}}
* ''Latrodectus hasselti ancorifer'' {{small|[[Władysław Kulczyński|Kulczyński]], 1911}}
* ''Latrodectus cinctus'' {{small|[rejected] [[Berta S. Gerschman de Pikelin|Gerschman]] & [[Rita D. Schiapelli|Schiapelli]], 1942}}
* ''Latrodectus mactans hasselti'' {{small|[[Pater Chrysanthus|Chrysanthus]], 1975}}
{{endplainlist}}
 | synonyms_ref        = <ref name=WSC_s39048>{{cite web |title=Taxon details ''Latrodectus hasselti'' Thorell, 1870 |work=World Spider Catalog |publisher=Natural History Museum Bern |url=https://wsc.nmbe.ch/species/39048 |access-date=12 May 2025|url-status=live }}</ref>
}}

The '''redback spider''' ('''''Latrodectus hasselti'''''), also known as the '''Australian black widow''',<ref name=":2">{{Cite journal|title=The multiple actions of black widow spider toxins and their selective use in neurosecretion studies|last=Ushkaryov|first=Y. A.|volume=213|issue=5|pages=527–42|journal=Toxicon|year=2004|doi=10.1016/j.toxicon.2004.02.008|pmid=15066411|bibcode=2004Txcn...43..527U }}</ref><ref>{{Cite book|title=Recent Insights in Latrodectus ("Black Widow" Spider) Envenomation: Toxins and Their Mechanisms of Action|last=Rodrigues Peres|first=O.|publisher=Springer|pages=333–44|year=2016|doi=10.1007/978-94-007-6389-0_23|isbn=978-94-007-6388-3}}</ref><ref name=":4">{{Cite book|chapter=Impact of Non-native Animals and Plants on Human Health|last=Nentwig|first=N.|title=Impact of Biological Invasions on Ecosystem Services|publisher=Springer|year=2017|pages=277–93| doi=10.1007/978-3-319-45121-3_18|isbn=978-3-319-45119-0}}</ref>  is a [[species]] of highly venomous [[spider]] believed to originate in Australia, but which is now found in [[Southeast Asia]]  and [[New Zealand]]. It has also been found in packing crates in the United States with colonies elsewhere outside Australia.<ref name=":5">{{Cite book|title=A field guide to spiders of Australia.|last=Whyte|first=Robert|date=2017|publisher=CSIRO Publishing|isbn=9780643107076|location=Clayton, VIC Australia|pages=321, 339|oclc=971943480}}</ref> It is a member of the [[Cosmopolitan distribution|cosmopolitan]] genus ''[[Latrodectus]]'', the widow spiders. The adult female is easily recognised by her spherical black body with a prominent red stripe on the upper side of her abdomen and an hourglass-shaped red/orange streak on the underside. Females usually have a body length of about {{convert|10|mm|sigfig=1}}, while the male is much smaller, being only {{convert|3|–|4|mm|in|abbr=on}} long.

Mainly nocturnal, the female redback lives in an untidy web in a warm sheltered location, commonly near or inside human residences. It preys on insects, spiders and small vertebrates that become ensnared in its web. It kills its prey by injecting a complex [[venom]] through its two fangs when it bites, before wrapping them in silk and sucking out the liquefied insides. Often, it first squirts its victim with what resembles 'superglue' from its spinnerets, immobilising the prey by sticking the victim's limbs and appendages to its own body. The redback spider then trusses the victim with silk. Once its prey is restrained, it is bitten repeatedly on the head, body and leg segments and is then hauled back to the redback spider's retreat. Sometimes a potentially dangerous victim can be left to struggle for hours until it is exhausted enough to approach safely.<ref name=":5" /> Male spiders and spiderlings often live on the periphery of the female spiders' web and steal leftovers. Other species of spider and [[parasitoid]] wasps prey on this species. The redback is one of a number of [[arachnid]]s that usually display [[sexual cannibalism]] while mating.

After mating, sperm is [[Female sperm storage|stored]] in the [[spermathecae]], organs of the female reproductive tract, and can be used up to two years later to fertilise several clutches of eggs. Each clutch averages 250 eggs and is housed in a round white silken egg sac. The redback spider has a widespread distribution in Australia, and inadvertent introductions have led to established colonies in New Zealand, the United Arab Emirates, Japan<ref>{{Cite news|url=https://theconversation.com/hidden-housemates-the-australian-redback-spider-55570|title=Hidden housemates: the Australian redback spider|last=Saez|first=Natalie J.|work=The Conversation|access-date=1 October 2017|language=en|archive-date=1 October 2017|archive-url=https://web.archive.org/web/20171001212848/https://theconversation.com/hidden-housemates-the-australian-redback-spider-55570|url-status=live}}</ref> and greenhouses in Belgium{{cn|date=March 2025}}.

The redback is one of the few spider species that can be seriously harmful to humans, and its liking for habitats in built structures has led it to being responsible for a large number of serious [[Spider bite#Spider venom|spider bites]] in Australia. Predominantly [[neurotoxic]] to vertebrates, the venom gives rise to the syndrome of [[latrodectism]] in humans; this starts with pain around the bite site, which typically becomes severe and progresses up the bitten limb and persists for over 24 hours. Sweating in localised patches of skin occasionally occurs and is highly indicative of latrodectism. Generalised symptoms of nausea, vomiting, headache, and agitation may also occur and indicate severe envenomation. An [[antivenom]] has been available since 1956.