Possible for a Redback spider to be in the US?

ReignofInvertebrates

Arachnoprince
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So I was cleaning and I found a dead spider. At first I thought it was just a black widow so I wasn't freaked out but now I'm thinking it's a Redback and I'm totally freaking out. What do you guys think?
It's pretty small. about the size of a piece of cat food
Location helps to distinguish between Latrodectus spp. I don’t think it’s hasselti, but to be fair their toxicity levels are pretty similar so it doesn’t make much of a difference if that’s what you’re concerned about.
 

Stainlesssteelrat

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I have noticed multiple examples of widows with red stripes down the back. I’d like to know what is the distinguishing feature that separates the red back from other widows? Multiple locations. I do pest control around industrial sites and run across many widows in bait boxes meant for mice. The majority of the sites are in eastern Washington which is a widow heaven. I can usually determine spider families by webbing. But I have ran across multiple instances of spiders with red stripes on the back and was wondering what is the distinguishing feature.
 

NYAN

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I have noticed multiple examples of widows with red stripes down the back. I’d like to know what is the distinguishing feature that separates the red back from other widows? Multiple locations. I do pest control around industrial sites and run across many widows in bait boxes meant for mice. The majority of the sites are in eastern Washington which is a widow heaven. I can usually determine spider families by webbing. But I have ran across multiple instances of spiders with red stripes on the back and was wondering what is the distinguishing feature.
These are all L. hesperus juvenile females. All North American black widow species have red markings besides an hourglass at some point in their life. The distinguishing factor here is range. You will probably never see an exotic widow species outside of its range unless it was transported. The habitat that you are seeing them in is not one where an exotic species would likely appear
 

darkness975

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If it's like @Smokehound714 says all over I suspect it will be like the Himalayan blackberry invasion in the pacific northwest. Essentially, obvious plans to take over the planet. However, environmental limiting factors came into play. So Geos prefer human habitation and are displacing Hesperus. But Hesperus has a huge range and widely differing environments. From the cold and constantly damp pacific northwest to the alkali flats on borders of death valley and south past the Salton Seat into Mexico. Opportunity invasives rarely are able to tolerate all the niches that the local animal populations have adapted to.
I hope that's true.
 

Ungoliant

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I have noticed multiple examples of widows with red stripes down the back. I’d like to know what is the distinguishing feature that separates the red back from other widows? Multiple locations. I do pest control around industrial sites and run across many widows in bait boxes meant for mice. The majority of the sites are in eastern Washington which is a widow heaven. I can usually determine spider families by webbing. But I have ran across multiple instances of spiders with red stripes on the back and was wondering what is the distinguishing feature.
It is common for juvenile black widows (of all species) to have red markings on their backs. Most native species outgrow these markings, although red spots often remain on Latrodectus variolus (the northern black widow).

Though you're unlikely to find them in Washington, L. variolus can be distinguished from L. hasselti (the redback spider) by the fact that L. variolus has a broken hourglass under her abdomen. (L. hasselti has a solid hourglass.)

Otherwise, range is generally the easiest way to rule out L. variolus. In North America, if you see a black widow with a red stripe, it's almost certainly one of our native widows (L. hesperus in your state). With global commerce, it's always possible for a species to be introduced from another continent, but as far as I know, we have no documented redback populations in the U.S.
 

SolarArachnophobia

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So I live in South TX and lately I’ve found two spiders that I’ve never really seen before in my house. (Two separate occasions) At first I thought they were black widows, but I’ve seen an one before and this one looks different from a black widow. So can someone help identify it? I wouldn’t want my siblings or dogs to get bitten and it be venomous. (ps i found the spider next to an also already dead scorpion recently)
 

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Albireo Wulfbooper

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So I live in South TX and lately I’ve found two spiders that I’ve never really seen before in my house. (Two separate occasions) At first I thought they were black widows, but I’ve seen an one before and this one looks different from a black widow. So can someone help identify it? I wouldn’t want my siblings or dogs to get bitten and it be venomous. (ps i found the spider next to an also already dead scorpion recently)
This is definitely not a redback. It happens to have red on its back, but it's certainly not in the same family as redbacks. I'm nowhere near an expert on spiders in your area, but it appears to be a species in the Castianeira genus - these are harmless ground spiders. you can see a similar one here: https://www.whatsthatbug.com/2015/10/06/ground-spider-5/
 

MarkB

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Is this a red back and black widow hybrid? On back porch in central Oklahoma.

5CC064BA-15CE-4F50-849B-4C371EF23AE9.jpeg 9B4BFAA5-2228-4858-A316-02A3ECA5C598.jpeg
 
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Albireo Wulfbooper

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Is this a red back and black widow hybrid?
That’s not a thing. Many of the native North American widow species have red markings on their dorsal side. I’ll let someone more versed in the US Latrodectus species give you an ID, but I am certain it will turn out to be a very normal local species.
 

MarkB

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That’s not a thing. Many of the native North American widow species have red markings on their dorsal side. I’ll let someone more versed in the US Latrodectus species give you an ID, but I am certain it will turn out to be a very normal local species.
OK thank you for the information. I’m definitely not an expert.
 

MarkB

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i thought the NA Black widow doesn’t have the orange stripe On the upper abdomen.
 

Albireo Wulfbooper

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OK thank you for the information. I’m definitely not an expert.
hey, me neither :) thankfully we do have experts here and they’re generous with their knowledge!

i thought the NA Black widow doesn’t have the orange stripe On the upper abdomen.
There are several different species in North America that can have a variety of red or orange markings at different times in their lives - juveniles can look quite different from adults, for instance, and even within a given species there can be a range of different markings. I’ve seen a bunch of North American black widows that have similar markings to what’s in your photos, but I’m not familiar enough with them to hazard an ID.
 

dangerforceidle

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In Oklahoma, all three native black widow species can be found: Latrodectus hesperus, L. mactans, and L. variolus. As others have noted, all three native species can exhibit red markings along their dorsal side all the way through adulthood.
 

Ungoliant

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In Oklahoma, all three native black widow species can be found: Latrodectus hesperus, L. mactans, and L. variolus. As others have noted, all three native species can exhibit red markings along their dorsal side all the way through adulthood.
L. variolus can likely be ruled out, as they typically have a broken hourglass.
 

JOinWV

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Hi everyone, this is my first time on this forum. I found it while searching for information about the spider pictured here. I am a home inspector living in the eastern panhandle of WV. Found this one under the porch of a house in the woods. I'm finding a lot of confusing information about redback vs. widows, juveniles...etc. Anyone have a guess at this one?
20210910_134044.jpg
 

Albireo Wulfbooper

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Hi everyone, this is my first time on this forum. I found it while searching for information about the spider pictured here. I am a home inspector living in the eastern panhandle of WV. Found this one under the porch of a house in the woods. I'm finding a lot of confusing information about redback vs. widows, juveniles...etc. Anyone have a guess at this one?
View attachment 398652
In that region it’s most likely to be the northern widow, Latrodectus variolus.
 

t2jbird

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Found in Kentucky? This could be either L. mactans (the southern black widow), or L. variolus (the northern black widow). Both are native to that state, and I’m not good enough to tell the difference.
Yep. Google Lens told me Red Back and here I am lol D18FCF62-C30E-4F56-AB6C-78C8AA5649CF.jpeg
 

Albireo Wulfbooper

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Yep. Google Lens told me Red Back and here I am lol View attachment 406122
Many Latrodectus species’ dorsal markings are highly variable, which makes them a poor candidate for identification by artificial intelligence. For some specimens, even experts would need to examine microscopic details to definitively discern between species. AI image interpretation is pretty good these days, but it’s very far from perfect, and it’s strongly limited by past input and by photo quality, angle, zoom level, lighting, etc. I like iNaturalist because it takes your location into account (which is a huge deal for arthropod identification), and because actual experts will provide corrections to identifications, often within days of uploading an image. Again, their AI is imperfect, but the experts on the platform make it so much better.

At any rate, you can rest assured that this is certainly a native species and not a redback.
 
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