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Possible for a Redback spider to be in the US?

Discussion in 'True Spiders & Other Arachnids' started by WiseWarrior, Aug 31, 2013.

  1. Smokehound714

    Smokehound714 Arachnoking Active Member

    there are a few people that have them in the USA. from a small introduced population i believe
  2. Ungoliant

    Ungoliant Malleus Aranearum Staff Member

    In immature black widow spider (family Theridiidae, genus Latrodectus). Do you have a photo of the egg sac? That can help identify the species.

    All three of our native species of black widow can be found in Oklahoma:

    While all widow spiders should be considered medically significant, bites from these spiders are rare. They generally occur when a person unwittingly sticks a bare hand into a spider's web, pressing it against the skin.
    Last edited: Sep 14, 2017
  3. The Snark

    The Snark هرج و مرج مهندس Old Timer

    Leaving myself wide open to @Ungoliant bellowing 'hair splitting pedant!' at me... five species in NA.
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  4. Ungoliant

    Ungoliant Malleus Aranearum Staff Member

    I was only listing the species of black widow that one would expect to find in Oklahoma.
    Last edited: Sep 14, 2017
  5. The Snark

    The Snark هرج و مرج مهندس Old Timer

    All (T)hree of our native species can be found in Oklahoma.
    I'll be under the floorboards if you want me.
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  6. kjmeredith901

    kjmeredith901 Arachnopeon

    Hi All,

    I live in Memphis, TN and found this lady in my garage. A google search led me here. Can you help me identify her? Thanks in advance for your help! spider.jpg
  7. kjmeredith901

    kjmeredith901 Arachnopeon

    It has since been suggested to me that this may be a male black widow, so now i feel dumb for calling it "lady". Can anyone confirm this?
  8. Ungoliant

    Ungoliant Malleus Aranearum Staff Member

    Likely a juvenile black widow. The female Latrodectus mactans will lose these extra markings as she matures. The female Latrodectus variolus has them even as adults. (Males of both species also have extra markings, but this does not look like a mature male.)
  9. kjmeredith901

    kjmeredith901 Arachnopeon

    @Ungoliant, Thanks for your help, I very much appreciate the information!
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  10. AshleyB

    AshleyB Arachnopeon

    I am in Oklahoma City. I have found 2 of these spiders in my house on base. They look a lot like the Redback Spider, but they aren't even "supposed" to be found in the United States. I really have no idea exactly what it is - I HATE spiders... Do you think it is a widow of some sort or a redback given the fairly straight line down the back of the spider?

    Attached Files:

  11. The Snark

    The Snark هرج و مرج مهندس Old Timer

    As @Ungoliant has said. And Redbacks are Widows, L. Hasselti.
    PS Good luck with your spider phobia. Consider avoiding playful kittens. They cause about 1,000,000 injuries bearing a potential infection for each significant spider bite.
    Last edited: Sep 29, 2017
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  12. AshleyB

    AshleyB Arachnopeon

    I appreciate your quick response. My concern is that in the research that I did, the redbacks may require an anti-venom unlike the black widows that are more commonly found in the United States. I have two small children and would prefer to know what I am dealing with if they did ever get bitten for any reason.

    PS. I'm not a cat person either, but thanks for the advice.
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  13. The Snark

    The Snark هرج و مرج مهندس Old Timer

    The most powerful (LD50-mice) venom in Latros is in a North American species, L Geometricus. However, this is not the determining factor in the (very rare) need for anti-venin.
    The determining factor is always the MMO, Means, Method and Opportunity. The most anti-venin ever prescribed for a patient was in fact an Australian man and a Hasselti was involved. The spider was trapped between his body and the bed and bit effectively multiple times. This is extraordinary and extraordinarily rare. The average Latro bite is usually trivial, described by one expert as a warning nip a dog would give. They will always run and hide if at all possible.

    Two Latro bites. The red, recent - L Hasselti, and the bump on my knuckle - L Hesperus, 30 years old. Neither was medically significant.

    LD50 values for some of the N.A. Latrodectus species:

    Latrodectus geometricus = .43 mg/kg (IV) & .223 mg/kg (IP)
    Latrodectus hesperus = .84 mg/kg (IV)
    Latrodectus mactans = 1.39 mg/kg (IV) & .90 mg/kg (SC)
    Latrodectus bishopi = 2.2 mg/kg (could be IP)
    Latrodectus variolus = 1.8 mg/kg (IP)

    (Data from @Widowman10 web site: https://sites.google.com/site/widowman10/)

    A report I read from the Museum and Art Gallery, Northern Territory, http://www.magnt.net.au/ had the LD-50 of Hasselti at .60-.85 mg/kg. Equivalent to Hesperus.
    Last edited: Sep 29, 2017
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  14. AshleyB

    AshleyB Arachnopeon

    Would the location of the bite look similar on a dog? This looks really comparable to a spot on my dog a few weeks ago. My initial thought is that it must have been a spider that bit him.
    Again thanks for your response!
  15. The Snark

    The Snark هرج و مرج مهندس Old Timer

    It certainly could, as any similar bite that infused an irritant substance. Examining the skin of the animal, specifically profusion, redness in the skin color normally and how the redness returns after pinching the skin then comparing it to your own skin, would be the best way to determine this.
  16. Ungoliant

    Ungoliant Malleus Aranearum Staff Member

    It isn't possible to diagnose a spider bite from the wound alone, even for a physician or veterinarian. (Many more common conditions are mistaken for spider bites.)
    Last edited: Sep 30, 2017
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  17. 20170706_121254.jpg 20170706_121549.jpg
  18. This was found at my cabin at Pickwick State Park in Counce Tn.
  19. dangerforceidle

    dangerforceidle Arachnoknight Active Member

    Tennessee is in range of Latrodectus mactans and L. variolus. I would suspect a sub-adult of one of these species, as both can have red dorsal markings (as Ungoliant stated above).

    Redback spider specifically refers to the Australian Latrodectus hasselti, but other widows can have red markings as juveniles or as adults. Check out L. tredecimguttatus for example:

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  20. pannaking22

    pannaking22 Arachnoking Active Member

    Looks like variolus, though it still could be mactans. Definitely not L. hasselti.

    Love me some treds, @dangerforceidle, always happy to see pics of them :)
    Last edited: Dec 6, 2017
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