Possible for a Redback spider to be in the US?

Smokehound714

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

Ungoliant

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Can someone help me to identify this spider? It was inside a toy outside and brought inside by my kiddo. It was guarding an egg sac.
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.
 
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The Snark

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

kjmeredith901

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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
 

kjmeredith901

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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?
 

Ungoliant

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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?
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.)
 

AshleyB

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Researching what kind of spider was on my front door led me here. Maybe you guys can help me figure it out. I looked at a lot of pictures and can't seem to decide on what I think it is. What do you guys think? I live in Oklahoma by the way.

View attachment 220981
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?
 

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The Snark

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Do you think it is a widow of some sort or a redback given the fairly straight line down the back of the spider?
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.
 
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AshleyB

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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.
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.
 

The Snark

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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.
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.
 
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AshleyB

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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!
 

The Snark

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Would the location of the bite look similar on a dog?
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.
 

Ungoliant

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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.
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.)
 
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JljenkinsII

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The white bands and broken stripe on the back are typical of juvenile Hasseltii. If you keep it and the white disappears while the red joins into a single stripe, it be Hasseltii. That would definitely be worth taking to a local university. Head scratching time how it got there.
Recent reports have them turning up in Europe and Japan.
20170706_121254.jpg 20170706_121549.jpg
 

dangerforceidle

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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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