# Loxosceles ( brown recluse spiders )



## Laurens (Apr 25, 2015)

after a few posts I thought it might be good to tell you something about my favorite spider species.
As in my last post someone had a question about the reason for keeping a specific spider.
Let me be the first to start with this subject 
If there's one spider to be interested in, brown recluse spiders could be that species to enjoy investigation.
The behaviour of recluse spiders is very interesting to watch as in hunting strategy's, night activity and communion behavior.
I beleave the toxicity of this spider is just coincidence when it comes to the sphingomyelinase D and its effect on the human body.
with this in mind I do not think of this spider as a serious threat as recluse spiders are ''reclusive'' like their names and only bite as last choice.
The damage caused by an accidental bite could go from minor ( blister.swelling like ) to medically urgent ( lesions/tissue damage ) possibly spreading.
best way to avoid being bitten, this offcourse counts for all venomous animals. for some its just a scary little spider, but for me its like a world to discover.
Im always trying to answere as much of the questions but for now I leave you guys with the 2 subspecies Im breeding with.

Loxosceles laeta ( Chilean recluse spider ) Adults








Loxosceles rufescens ( Mediterranean recluse spider ) juveniles

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## pannaking22 (Apr 25, 2015)

Very cool! They are a very interesting genus.

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## Laurens (Apr 27, 2015)

they truly are pannaking22  its not just an ordinary spider to be afraid of


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## Rick McJimsey (Apr 27, 2015)

I'd love to get some laeta. Currently growing up some reclusa and rufescens.


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## Laurens (Apr 27, 2015)

Great species Rick, I would love to have reclusa but I haven't found them yet.
they are on my wanted list like L.intermedia and L.deserta


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## pannaking22 (Apr 27, 2015)

After reading through Rick Vetter's book, I wouldn't mind getting some African species as well.


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## antinous (Apr 27, 2015)

Wouldn't mind getting a few of my own either, when I get my own place. I'd love to collect all the species and see how their behavior ranges, as well as with the rest of the Sicariidae family.


Sent from my iPhone using Tapatalk

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## Venom (Apr 28, 2015)

Just a reminder...but the L. laeta, L. intermedia, L. gaucho population in Santiago, Chile, causes regular fatalities. According to a study submitted to the National Institutes of Health, the collective fatality rate of these three species (mostly due to L. laeta) is 3.7% (1 death per 27 cases...which is not a funny stat), and serious blood and kidney poisoning occurs in 15.7% of bites (1 in every 6 cases of envenomation). Source: http://www.ncbi.nlm.nih.gov/pubmed/2577020

Those are some sobering stats! Why such high numbers of serious envenomation? Because the venom of L. laeta contains an ORDER OF MAGNITUDE (meaning 10 times!) more sphingomyelinas-D than does L. reclusa. "It is striking that venoms of L. laeta and Sicarius yielded an order of magnitude more total venom protein upon electrostimulation than the other Loxosceles species surveyed" - Source: http://www.lclark.edu/~binford/SMDDistribution copy.pdf

L. laeta should not be treated like L. reclusa, which generally has only mild to moderate local results and very rarely systemic symptoms. L. laeta has a HIGH prevalence of systemic poisoning, with a rate of fatality almost on par with Tityus serrulatus, and a rate of local poisoning of above 84%. Conclusion? Loxosceles laeta should be treated with as much caution as Sicarius spp.

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## antinous (Apr 28, 2015)

^That's pretty interesting! I was wanting to find out if one species is 'more' venomous than the other, guess this makes it easier haha. I know there's a species of snake (possibly cobra? forgot, was a while ago) that occurs  in Sri Lanka and India. One was more toxic than the other, but I forgot which one was. Anyways, it's always interesting to see if one subspecies is more potent than the other.

I'd still treat every venomous animal with the same respect, be it deadly or not, but that's just me.


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## Venom (Apr 28, 2015)

Pampho85 said:


> ^That's pretty interesting! I was wanting to find out if one species is 'more' venomous than the other, guess this makes it easier haha. I know there's a species of snake (possibly cobra? forgot, was a while ago) that occurs  in Sri Lanka and India. One was more toxic than the other, but I forgot which one was. Anyways, it's always interesting to see if one subspecies is more potent than the other.
> 
> I'd still treat every venomous animal with the same respect, be it deadly or not, but that's just me.


 I'm glad you enjoyed the info! Just FYI, L. laeta isn't a subspecies of L. reclusa though, but a full species on its own. There are over 50 species of Loxosceles "brown spiders" / "recluse spiders," and there is a great range of toxicity in the genus, from nearly-benign species like L. deserta to very seriously venomous species like L. laeta and the other Chileans.

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## antinous (Apr 28, 2015)

Venom said:


> I'm glad you enjoyed the info! Just FYI, L. laeta isn't a subspecies of L. reclusa though, but a full species on its own. There are over 50 species of Loxosceles "brown spiders" / "recluse spiders," and there is a great range of toxicity in the genus, from nearly-benign species like L. deserta to very seriously venomous species like L. laeta and the other Chileans.


Thanks for catching my mistake haha. I only just started reading some papers on them to learn more, and even tho I read they're different species, it's still engrained in my head they're subspecies for some reason aha.

That does remind me, while in Peru, a professor had brought back a Loxosceles sp. At that time I wasn't too into true spiders, as I am now, so I just wrote it off as L. reclusa, which was obviously wrong. Looking back, I wish I was able to take photos of it to see which species it was aha.


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## pannaking22 (Apr 28, 2015)

Pampho85 said:


> Thanks for catching my mistake haha. I only just started reading some papers on them to learn more, and even tho I read they're different species, it's still engrained in my head they're subspecies for some reason aha.
> 
> That does remind me, while in Peru, a professor had brought back a Loxosceles sp. At that time I wasn't too into true spiders, as I am now, so I just wrote it off as L. reclusa, which was obviously wrong. Looking back, I wish I was able to take photos of it to see which species it was aha.


Photos might not have helped you too much since there's so much similarity between Loxo sp. and coloration isn't as helpful because they can change color to an extent depending on what they last ate (from Rick Vetter's recluse book). Identification will likely come down to checking out the genitals because that's how arthropod taxonomy works anymore lol. 

Great post as always, Venom, and a good reminder to people that (potentially) highly venomous spiders aren't something to be messed with.

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## antinous (Apr 28, 2015)

pannaking22 said:


> Photos might not have helped you too much since there's so much similarity between Loxo sp. and coloration isn't as helpful because they can change color to an extent depending on what they last ate (from Rick Vetter's recluse book). Identification will likely come down to checking out the genitals because that's how arthropod taxonomy works anymore lol.
> 
> Great post as always, Venom, and a good reminder to people that (potentially) highly venomous spiders aren't something to be messed with.


Ah, thanks for the heads up. And now I really want his book haha.

Most be hard to keep the different species then since they do look similar then.


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## Hanska (Apr 30, 2015)

A question just popped in my head. Can Loxosceles spp. climb glass/smooth plastic?


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## The Snark (Apr 30, 2015)

Pampho85 said:


> ^That's pretty interesting! I was wanting to find out if one species is 'more' venomous than the other, guess this makes it easier haha. I know there's a species of snake (possibly cobra? forgot, was a while ago) that occurs  in Sri Lanka and India. One was more toxic than the other, but I forgot which one was. Anyways, it's always interesting to see if one subspecies is more potent than the other.
> 
> I'd still treat every venomous animal with the same respect, be it deadly or not, but that's just me.


Probably Russells viper. The colder the clime, the more hemotoxin is present in the venom which aids in prey digestion. Unlikely to be similar to spider venom variations between species, but something to consider.


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## pannaking22 (Apr 30, 2015)

Hanska said:


> A question just popped in my head. Can Loxosceles spp. climb glass/smooth plastic?


Not very well from what I've seen. If there are little scratches they can sometimes get footholds, but they aren't great at climbing smooth surfaces.

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## Hanska (May 1, 2015)

pannaking22 said:


> Not very well from what I've seen. If there are little scratches they can sometimes get footholds, but they aren't great at climbing smooth surfaces.


Ok, thanks. I've been thinking about L.laeta but this thread has put some new insight on the subject. I guess the ms. has a good point to deny me one. Not that the Latros or the Sicarius puts her off put Loxos she finds ugly. And I think "It's not that bad" no longer cuts it.
And thanks for the paper Venom. I had no idea L.laeta was that much of the scale.


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## Laurens (May 5, 2015)

its been a while, sorry busy busy days 
About Loxosceles venom, there are a lot in researchers who tried to find out the differences between the venom of all the species of recluse spiders.
Due the fact that the Chilean recluse spider is the largest species of recluse spider it pretty obvious that they contain a larger amout of venom, not nessacarely more toxic.
Yes I´d beleave there are some variations but in context with the damage it can cause, in my personal oppinion its the amount of venom what differentiate the dangerousness.
All species of Loxosceles have a very tiny amount of venom in their glands and most subspecies don´t even grow big enough to posess a real danger to a human being.
about the climbing, recluse spiders usually don´t climb on smooth surfaces this goes for adult specimens. but they still can climb on every little scratch or between small surfaces 
including glass when there´s less room between it so it can press itself up or using a tiny bit of their web on their legs.
The documents above are really interesting offcourse, and I´m familiar with the work of Grady binford so its really reliable information.

at the end I need to show you guys something that made me really happy yesterday !!


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## pannaking22 (May 5, 2015)

Nice, congrats on the sac! Which species is that?


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## Laurens (May 5, 2015)

thanks, Loxosceles laeta

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## Venom (May 5, 2015)

Laurens said:


> its been a while, sorry busy busy days
> About Loxosceles venom, there are a lot in researchers who tried to find out the differences between the venom of all the species of recluse spiders.
> Due the fact that the Chilean recluse spider is the largest species of recluse spider it pretty obvious that they contain a larger amout of venom, not nessacarely more toxic.
> Yes I´d beleave there are some variations but in context with the damage it can cause, in my personal oppinion its the amount of venom what differentiate the dangerousness.


Sorry Laurens, but no. The study I referenced in my last post did look at the concentration of L. laeta venom, and found it to be 10 times more concentrated than L. reclusa venom. The science has been done; their venom is qualitatively different (FAR more potent!!!) than the common North American recluse varieties, as well as far more potent than L. rufescens. That difference in potency is IN ADDITION to their quantitative advantage in simply having more venom than smaller species. Remember, the venom yield of a spider is dependent on its volume, not its diameter in legspan. So, if the legspan doubles, the venom yield is eight times greater (my wife is a mathematician, and figured out the exponential increase for me.  ).



> All species of Loxosceles have a very tiny amount of venom in their glands and most subspecies don´t even grow big enough to posess a real danger to a human being.


Again, that simply isn't true. The study I linked to earlier showed the results of L. laeta bites, as observed in the hospitals of Santiago, Chile. The study reported a fatality rate of 3.7%, and a rate of serious blood and kidney poisoning of 15.7%. That means that ****EVEN WITH MEDICAL TREATMENT IN A HOSPITAL!!!**** Loxosceles laeta killed 1 in 27 bite victims observed in this study. However, 1 in 6 patients of L. laeta envenomation had VERY serious symptoms of systemic cytotoxicity. I think that definitely counts as a real danger to a human.

This means that your impression of L. laeta as "not necessarily more toxic" than other recluses, and that they "don't even grow big enough to possess a real danger to a human being," is simply and completely wrong. Loxosceles laeta is a large spider, far larger than the average Latrodectus, and it has a significant quantity of highly toxic venom. Your opinion isn't matching up with the science, nor with the hospital observations in its native country.


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## The Snark (May 5, 2015)

Venom, what is missing from your data is bites per year per capita. That would put the significance in clear contrast. If you could dig up the info??

As it stands, that venom toxicity is placing Laeta up with phoneutria and venomous snakes. Far above trifles like latrodectus which has,  if memory serves, 1 medically significant bite in several hundred.


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## Laurens (May 7, 2015)

to start with the Chilean recluse, I did not ment it that way that the recluse spiders aren't getting big enough
but they can only penetrate the skin after the first 3/4 molts whats makes the adult specimens a potential threat.
As for the Chilean recluse these are the largest of there kind with a large quantity of toxine. 
Im open for all kind of new information as we all need to grow in arachnology.
The documents for the chile recluse bite doesn't tell if this goes mainly about children, eldery or people with a bad health.
Based on clinical evidence in LA county there haven't been one reported bite in the last 80 years what makes it difficult to research in some locations.
you've probably heard about the pyramid method for bites ( bottem = Minor ) ( Top = serious damage ) as for the L.reclusa 90% of the bites are placed in the minor
or on partition above it ( modererate = swelling/blisters ) but most are selfhealing. The chilean relcuse does not live in close proximity to humans and that's probably 
the reason why there's not much information on bite reports. Many bites are not even noticed or that minor they are not notecable for a bite rapport.
than we got the differences between fat perscentage, thin/slender people are less in danger for tissue death as the thicker ones because they got more tissue to destroy.
L.rufescens excists since 1967 probably after a misidentification It might have been there many years earlier. the mediterranean recluse is considered to have less potent venom
than the brown recluse spider but the pyramid I told about before is something to remind you cause all loxosceles species have sphingomyelinase D and no matter of the amount
its not something to neglect.

and offcourse if there are more scientific documents, place it in here as we are here to learn from eachother


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## Venom (May 28, 2015)

The Snark said:


> Venom, what is missing from your data is bites per year per capita. That would put the significance in clear contrast. If you could dig up the info??
> 
> As it stands, that venom toxicity is placing Laeta up with phoneutria and venomous snakes. Far above trifles like latrodectus which has,  if memory serves, 1 medically significant bite in several hundred.


So I have done some digging, and found this: a Google preview of a book which I really need to buy, entitled _Arthropod Venoms_, edited by S. Bettini. The material I have uploaded is from Chapter 11: "Venoms of Scytodidae. Genus Loxosceles," by H. Schenone and G. Suarez. In it I have found some pretty great data. As Google Books doesn't allow copy/pasting, I took some screenshots.


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## Venom (May 28, 2015)

Hmm...my crops didn't come out too legibly. Give me a minute and I'll get more legible versions uploaded here.


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## Venom (May 28, 2015)

These should be more legible:


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## Venom (May 28, 2015)

This book preview has a LOT more information, but the selections I've given were the relevant portions per your question, Snark. I hope this helps?


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## TheScorpionMan (Jun 2, 2015)

Bit of a nasty bite on that one


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## Chris LXXIX (Jun 2, 2015)

To be honest, no. I can't speak for _Loxosceles laeta_ but here where i live, back in the good first half of '80 (as a child, with my brother) we captured a lot, during years, in summer, of  _Loxosceles rufesces_, without know of course, nothing about their powerful venom.
I don't find them much intriguing, except for those creepy eyes, ah ah. I think _Cheiracanthium punctorium_ are more funny.
However, congrats for your spiders.

P.S
Obviously, while not "aggressive" spiders (they aren't a _Pterinochilus murinus_, at the end), their venom effects can be something terrible. A man last year lost completely a finger (amputation needed) due to a bite of _Loxosceles rufesces_ and from what i know the South American ones are more even badass.
They are _Sicariidae_, and for lots of valid reasons.


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## antinous (Jun 23, 2016)

Don't mean to bump up an old thread, but now that I have my own place, I'm still looking for Loxosceles sp., does anybody know where to get them/or any breeders that breed them?


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## RebelWolf (Jun 24, 2016)

Cool. Nice looking recluses


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