# Most venmous spider of North America.



## Twillis10 (Jan 17, 2012)

Hi everyone,

I need help finding a top 5 list of the most venomous spiders of North America. I know there are tons of list on google, I just find that most are untrustworthy. I am a graphic design student and I am doing an info graphic on venomous spiders, snakes, and scorps in North America. A list with the LD50 would be nice, but not necessary. Thanks. If you know of a good scorp list as well let me know. Thanks.


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## BigJ999 (Jan 17, 2012)

Most venomous spider the black widow/southern black widow but all of that sp has highly toxic venom LD50 of 00.09mg. Arizona bark scorpion is the most dangerous scorpion in north America,most venomous snake is the Eastern coral snake to be honest LD50 doesn't mean much a Eastern coral snake's venom is extremely toxic and it takes about a drop to kill a full grown man. Some Rattlesnakes like the Canebrakes and the Tiger, Mojave,southern pacific also have highly potent neurotoxic venom and have killed people.


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## Ciphor (Jan 17, 2012)

Twillis10 said:


> Hi everyone,
> 
> I need help finding a top 5 list of the most venomous spiders of North America. I know there are tons of list on google, I just find that most are untrustworthy. I am a graphic design student and I am doing an info graphic on venomous spiders, snakes, and scorps in North America. A list with the LD50 would be nice, but not necessary. Thanks. If you know of a good scorp list as well let me know. Thanks.


We only have 2 types of spiders considered to have medically significant venom. Widows and Fiddle Backs. Hobos, yellow sacs, etc. all have lots of neat internet stories, but in the lab the venom is shown to be no more dangerous then a bee sting.

Top 5 in order in my opinion are:

_Latrodectus mactans_ (southern widow)
_Latrodectus bishopi_ (red widow)
_Latrodectus geometricus_ (brown widow)
_Loxosceles laeta_ (chilean recluse)
_Loxosceles reclusa_ (brown recluse)


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## Venom (Jan 17, 2012)

To my knowledge, we have no mortality information for Latrodectus bishopi.  The L. geometricus is definitely less dangerous than any of the three "black" widows of North America--all of which have caused fatalities in the USA whereas L. geometricus has caused zero fatalities in the USA and barely any abroad either.

Ｉ would rank the top five as:

(NOTE: the spider known as "THE black widow spider" is actually 3 distinct species of the same family that look very similar but have important differences.)

_Latrodectus hesperus_    (western black widow) This is the largest black widow species in North America.
_Latrodectus variolus_    (northern black widow) 
_Latrodectus mactans _   (southern black widow) The smallest black widow in North America.
_Loxosceles laeta_    (Chilean recluse: non-native/ introduced). This spider has a 3.7% fatality rate, and a 13% occurrence of serious kidney poisoning. (cite: http://www.ncbi.nlm.nih.gov/pubmed/2577020 )
_Loxosceles reclusa_    (brown recluse) This is the worst of our 11 native Loxosceles "recluse" spiders. Fatality is very very low, but ugly lesions are not uncommon. Occasionally the tissue damage can be very dramatic. Kidney poisoning (viscerocutaneous loxoscelism) is rare, but has happened, and can be life-threatening.

All other spiders in North America pale in toxicity to these five. The L. bishopi and L. geometricus are minimally toxic in comparison with the top three widows. There are also at least two species of "sac spider" ( genus Cheiracanthium) in North America that can cause unpleasant dermal blistering, swelling and pain, but are not life-threatening, nor capable of causing large-scale tissue damage like the Loxosceles "recluse spiders" can.


Scorpion LD50: 

http://web.singnet.com.sg/~chuaeecc/venom/rpotent.htm

http://www.terra-animals.de/LetaleDosis/Scorpiones

Basically, the top scorpions would be:

_Androctonus australis_ (kills the most people per year--_slightly _less potent than L. quin, but has over 2x the venom quantity)
_Leiurus quinquestriatus_ (highest scorpion venom potency known)

Followed by something like:
_Hemiscorpius lepturus_ (a nasty cytotoxic scorpion--it causes only 10% of the hospitalized scorpion stings in Iran ( which has A. crassicauda) but causes 90% of the reported deaths from scorpion envenomation. It doesn't look intimidating, but it's effects are horrid.)
_Androctonus mauritanicus
Androctonus crassicauda_

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## Ciphor (Jan 17, 2012)

My bad, I thought we were discussing the most venomous spider, not the deadliest. My list changes entirely if this is a deadliest list and not a most venomous.

_L. mactans_ to the best of my understanding has the most virulent venom out of the NA widows, but injects a very small amount when a bite occurs.

_L. hesperus_ is the opposite having the weakest venom, however injects substantially more of it. _L. hesperus_ also has much more opportunity to bite humans, having a slight range advantage.

_L. bishopi_ having a zero death rate makes sense, it is rarely encountered by humans and is highly restricted in where it is found. Ditto for _L. geometricus_ having only recently started establishing outside of Florida. These two are also far less observed and studied.

It is important also to understand discussing death rates, complicates things immensely in my opinion, as you have allergic factors, and opportunity factors. A more common widow will have more opportunity to bite a human, more opportunity with more bites to encounter an allergic person, all leading to a higher death rate. On the other hand measuring the virulence of a spiders venom is consistent.

I'm no Theridid expert, how would you line the spiders up based purely on virulence measurement Venom? Do you have any data on the venom potency measurements?

---------- Post added 01-17-2012 at 10:39 PM ----------

Also, I believe it was originally Emerton, or Kaston who stated "_Latrodectus mactans is the largest spider of the family Theridiidae._".

I believe _L. hesperus_ has the largest DLS, but lacks in weight compared to _L. mactans_.

http://animaldiversity.ummz.umich.edu/site/accounts/information/Latrodectus_mactans.html

I have not seen many in person, I judge based on published expert research.


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## MrCrackerpants (Jan 17, 2012)

Venom said:


> To my knowledge, we have no mortality information for Latrodectus bishopi.  The L. geometricus is definitely less dangerous than any of the three "black" widows of North America--all of which have caused fatalities in the USA whereas L. geometricus has caused zero fatalities in the USA and barely any abroad either.
> 
> Ｉ would rank the top five as:
> 
> ...


Thanks for this great info. I would add this:

http://bugguide.net/node/view/33527

Does anyone have a distribution map for the Latrodectus genus?


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## Rick McJimsey (Jan 18, 2012)

MrCrackerpants said:


> Does anyone have a distribution map for the Latrodectus genus?


I'd also be interested in an in-depth map.


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## loxoscelesfear (Jan 18, 2012)

http://bugguide.net/node/view/1999/data
http://www.venombyte.com/venom/spiders/western_black_widow.asp
http://bugguide.net/node/view/1999/data

it's a start...  good thread btw


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## The Snark (Jan 18, 2012)

The criteria of the list needs to be clearly established. Is it possessing the most potent venom, causing the most injuries and deaths, or causing the most human deaths?
Not meaning to split hairs. Just to give an example, the most human deaths from snakes are the top 4, King cobra, the kaouthia, the krait and the Russells viper. However, these are not the most toxic venom wise. The list reflects the proximity of humans with venomous snakes.
Widowman10 has posted on his site which shows the LD50 of the various Latros: https://sites.google.com/site/widowman10/venom


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## MrCrackerpants (Jan 18, 2012)

loxoscelesfear said:


> http://bugguide.net/node/view/1999/data
> http://www.venombyte.com/venom/spiders/western_black_widow.asp
> http://bugguide.net/node/view/1999/data
> 
> it's a start...  good thread btw


ThanksThanksThanksThanksThanks


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## Ciphor (Jan 18, 2012)

The Snark said:


> The criteria of the list needs to be clearly established. Is it possessing the most potent venom, causing the most injuries and deaths, or causing the most human deaths?
> Not meaning to split hairs. Just to give an example, the most human deaths from snakes are the top 4, King cobra, the kaouthia, the krait and the Russells viper. However, these are not the most toxic venom wise. The list reflects the proximity of humans with venomous snakes.
> Widowman10 has posted on his site which shows the LD50 of the various Latros: https://sites.google.com/site/widowman10/venom


I gotta question the LD50 rating on _L. geometricus_. I firmly believe Richard Vetter is the foremost authority on _Latrodectus_ & _Loxosceles_, and having spoken with him on numerous occasions, he believes _L. geometricus_ may have one of the most virulent venoms of any of the latros, but completely lacks the ability to deliver a substantial amount of venom with the bite.

http://cisr.ucr.edu/brown_widow_spider.html

He is still collecting sample data, but is confident he will expose _L. geometricus_ as having some pretty potent stuff.

Snark I agree. All to often debates on venom become convoluted by mistaking virulence with death rates. Hopefully we provide the OP with enough information. Some good info here, even if there is debate on which latro packs the biggest punch


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## The Snark (Jan 18, 2012)

Ciphor said:


> I gotta question the LD50 rating on _L. geometricus_. I firmly believe Richard Vetter is the foremost authority on _Latrodectus_ & _Loxosceles_, and having spoken with him on numerous occasions, he believes _L. geometricus_ may have one of the most virulent venoms of any of the latros, but completely lacks the ability to deliver a substantial amount of venom with the bite.
> 
> http://cisr.ucr.edu/brown_widow_spider.html
> 
> ...


Yups. The theoretical meeting the practical nearly always sets off some form of debate. That sea snake with extremely virulent venom yet almost incapable of delivering it to a human, O. Hannah delivering such a great quantity it could kill humans with apple cider vinegar as venom, and so on. A basic formula, as scientific as possible, could help a lot in this. The venom virulence combined with other factors such as delivery ability and how great the population of venomous animal to prey/victim ratio. At a glance I would guess Hesperus is the #1 going by it having a pretty high LD50, a capable delivery mechanism, an extremely large distribution area, and a high population density in metropolitan areas.

I can't entirely agree with Vetter's contention: "Considering that the brown widow is less dangerous and may be supplanting the native western black widow from habitats, it is conceivable that the risk of serious injury from overall spider bite may decrease in southern California as the brown widow spreads."
This implies competitiveness between the species which is very unlikely and not established. The only animal that deliberately and specifically hunts latro is the Road Runner but it has not made any long term proven dent in the population. Prey availability does not seem to be a factor at all as demonstrated by the Hesperus near Death Valley and Hasselti in areas of the Australian outback, both well established in extremely 'prey hostile' environments.


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## Ciphor (Jan 18, 2012)

I don't agree with it either, or really any of his moral stances on spiders (he does substantial research in pest control). If you ever talk to him tho, the guy is brilliant about venomous spiders. His research in Sicariidae alone is amazing.


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## John Apple (Jan 19, 2012)

As far as the brown widow goes.....they have been in Florida for over 30 years...this is my personal observation
They are also in Texas..California...well all along that side of the country....Traveling down I-75 from Michigan to Florida [done the trip a lot] they are as far north as the Kentucky-Tennessee border.....
As far as deadliest....this still could remain to be seen

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## John Koerner (Feb 9, 2012)

Ciphor said:


> My bad, I thought we were discussing the most venomous spider, not the deadliest. My list changes entirely if this is a deadliest list and not a most venomous.
> _L. mactans_ to the best of my understanding has the most virulent venom out of the NA widows, but injects a very small amount when a bite occurs.
> _L. hesperus_ is the opposite having the weakest venom, however injects substantially more of it. _L. hesperus_ also has much more opportunity to bite humans, having a slight range advantage.
> _L. bishopi_ having a zero death rate makes sense, it is rarely encountered by humans and is highly restricted in where it is found. Ditto for _L. geometricus_ having only recently started establishing outside of Florida. These two are also far less observed and studied.
> ...


I asked Dr. Edwards, Curator of Arachnida & Myriapoda for the Florida State Collection of Arthropods, the same question regarding the Red Widow (_Latrodectus bishopi_) and he said its venom is highly-toxic, basically on a par with the Black Widow (_Latrodectus mactans_), but because Red Widows are found in palmetto fronds (as opposed to being in garages and houses too), there is virtually zero chance of being bitten by one.

Therefore, the question of "virulent venom" and "likelihood/danger of exposure" are two different questions ... but the Red Widow is every bit as venomous as the Black Widow, but it is by no means as dangerous (unless a person is planning to take up residence in a bed of palmetto fronds in Central Florida:biggrin:

Jack

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## Widowman10 (Feb 9, 2012)

John Koerner said:


> I asked Dr. Edwards, Curator of Arachnida & Myriapoda for the Florida State Collection of Arthropods, the same question regarding the Red Widow (_Latrodectus bishopi_) and he said its venom is highly-toxic, basically on a par with the Black Widow (_Latrodectus mactans_), but because Red Widows are found in palmetto fronds (as opposed to being in garages and houses too), there is virtually zero chance of being bitten by one.
> 
> Therefore, the question of "virulent venom" and "likelihood/danger of exposure" are two different questions ... but the Red Widow is every bit as venomous as the Black Widow, but it is by no means as dangerous (unless a person is planning to take up residence in a bed of palmetto fronds in Central Florida:biggrin:
> 
> Jack


that makes sense to me seeing as how they seem to be very similar to the variolus found down there. i wouldn't put any stock in it, but i could understand that. bishopi and variolus seem to be very similar to each other in many different ways.


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## OBT1 (Feb 15, 2012)

I know black widows and recluses are dangerous.:biggrin:


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## Jared781 (Feb 15, 2012)

I would have to say the Brown Recluse is up there!

---------- Post added 02-15-2012 at 12:15 PM ----------

this is a cool little chart 

http://s2.hubimg.com/u/3634381_f520.jpg


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## Ciphor (Feb 15, 2012)

Jared781 said:


> I would have to say the Brown Recluse is up there!
> 
> ---------- Post added 02-15-2012 at 12:15 PM ----------
> 
> ...


That chart is a peice of garabage (no offense)

That is exactly the crap entomologist like Rod and Rick battle that feeds miss-information.

Wolf spiders *are not dangerous*
Hobo spiders *are not dangerous*
Black House spiders *are not dangerous*
etc.

And <edit> "Toxic (poisonous)" so are they implying that if you eat a mouse spider or wolf spider it will be harmful?

Read published research that is creditable like the attached file on Hobo toxicology. Some neat pictures made in MSpaint then posted to a blog does not constitute "Science".

NOTE: Sorry about the language Mods/admin, wont happen again.

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## Venom (Mar 15, 2012)

John Koerner said:


> I asked Dr. Edwards, Curator of Arachnida & Myriapoda for the Florida State Collection of Arthropods, the same question regarding the Red Widow (_Latrodectus bishopi_) and he said its venom is highly-toxic, basically on a par with the Black Widow (_Latrodectus mactans_), but because Red Widows are found in palmetto fronds (as opposed to being in garages and houses too), there is virtually zero chance of being bitten by one.
> 
> Therefore, the question of "virulent venom" and "likelihood/danger of exposure" are two different questions ... but the Red Widow is every bit as venomous as the Black Widow, but it is by no means as dangerous (unless a person is planning to take up residence in a bed of palmetto fronds in Central Florida:biggrin:
> 
> Jack


That's really interesting, and I applaud your legwork on this. But...he is assuming this, or does he have a study he's basing that view on? I've never seen an LD50 test done on L. bishopi....or really any other toxinological analysis on that species. I'd be interested to know HOW he knows this.


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## cacoseraph (Mar 15, 2012)

Ciphor said:


> And <edit> "Toxic (poisonous)" so are they implying that if you eat a mouse spider or wolf spider it will be harmful?



this is mainly a hobby artifact (and one i supported until i actually started reading non-hobby lit). a lot of the actual invert literature i read uses poisonous and venomous interchangeably.  i have reptile friends who tell me the more modern reptile lit does try to make a distinction, but as far as bugwork goes, i got to go with the experts i read...

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## Ciphor (Mar 15, 2012)

cacoseraph said:


> this is mainly a hobby artifact (and one i supported until i actually started reading non-hobby lit). a lot of the actual invert literature i read uses poisonous and venomous interchangeably.  i have reptile friends who tell me the more modern reptile lit does try to make a distinction, but as far as bugwork goes, i got to go with the experts i read...


Well, technically, a venom is a poison. However, in regards to zoology & more importantly the medical field, a distinct line has been drawn between venom & poison.

Since this board, and blogs about spiders being medically significant, are in the realm of medicine & zoology, calling a venom a poison would be miss-leading & considered by most, inaccurate.

Wikipedia has a pretty modern and accepted definition.

"_In the context of biology, poisons are substances that cause disturbances to organisms,[1] usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism. The fields of medicine (particularly veterinary) and zoology often distinguished a poison from a toxin, and from a venom. Toxins are poisons produced via some biological function in nature, and venoms are usually defined as toxins that are injected by a bite or sting to cause their effect, while other poisons are generally defined as substances absorbed through epithelial linings such as the skin or gut._"

Goes into further detail if anyone is interested. http://en.wikipedia.org/wiki/Poison

I think if you are taking about it in a broad general sense, it is fine "_many organisms are poisonous such as frogs, snakes & spiders_". However when you are discussing it in terms of medical significance, you should use the proper terms, "_Atrax robustus is considered one of the most venomous spiders in Australia_".

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## The Snark (Mar 16, 2012)

*For the sake of clarity*

Venom: the poisonous fluid that some animals, as certain snakes and spiders, secrete and introduce into the bodies of their victims by biting, stinging, etc. 

Poison: a substance with an inherent property that tends to destroy life or impair health. 

Therefore, all venoms are poisons but not all poisons are venoms. Spiders possess venom with which they poison their victims. 

The difference in this little morass of nomenclature can be found in the word 'envenomate'. To inject or otherwise deliver a poison. Spiders envenomate, a verb. They do not poison, verb, as envenom is a more accurate and defining terminology.


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## cacoseraph (Mar 17, 2012)

no, i'll find some of the papers i've read.  the actual workers in the field of arachnology use the terms all but interchangeably.  generally, in science, you use the terms as used by the experts in that particular field


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## The Snark (Mar 17, 2012)

Riddle me this: Spiders are generally termed as venomous but snakes are commonly referred to as poisonous. However, the extract of both, in a laboratory, is usually referred to as venom.

Then we have the common usage. "That is snake/spider poison" will normally be taken as a poison that kills snakes/spiders. But "that is snake/spider venom"  can only be taken as the toxin from said animal.


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## cacoseraph (Mar 19, 2012)

http://www.americanarachnology.org/gallery_araneae.html
lots of links to papers that call it poison
https://www.google.com/webhp?source....2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1333&bih=645


2010
http://www.scielo.br/pdf/bjb/v71n3/21.pdf

2008
http://www.pnas.org/content/105/52/20781.full.pdf <-- Paleontological arachnologists
http://www.zoosprint.org/ZoosPrintNewsLetter/Bugs_R_all_No16_July2008.pdf

2005
http://www.pdn.ac.lk/cjsbs/text/text34.7.pdf <-- awesome paper on Poecilotheria from Sri Lanka
p. 85

2003
http://docserv.uni-duesseldorf.de/servlets/DerivateServlet/Derivate-2567/567.pdf  disertation paper (?) from University of Dusseldorf, Germany

2001
http://www.iisc.ernet.in/currsci/nov102001/1170.pdf

2000
http://journals.tubitak.gov.tr/zoology/issues/zoo-01-25-3/zoo-25-3-10-0005-10.pdf
http://edis.ifas.ufl.edu/pdffiles/IN/IN31700.pdf University of Florida paper originally published in 2000

1996
pdf of slides for a presentation based on  Foelix, R. F. 1996. Biology of Spiders, 2nd Ed
http://aces.nmsu.edu/academics/richmanresearch/documents/epws-4512sm.pdf


1992
http://www.sdu.edu.tr/dergi/fendergisi/english/cilt2(2)/cilt2_sayi2_126-135.pdf <-- citation to a 1992 paper that has poison in title

1991
http://palaeontology.palass-pubs.org/pdf/Vol 34/Pages 241-281.pdf <-- Paleontological arachnologists
p. 247 (image pdf, not findable)

1986
http://www.sdu.edu.tr/dergi/fendergisi/english/cilt2(2)/cilt2_sayi2_126-135.pdf <-- citation to a paper from 1986 with poison in title

1975
p. 276 (can't find for it, i think it is an image pdf)
http://academics.holycross.edu/files/biology/Z_morph_Tiere_v81_p257.pdf

1967 
Levi
http://hbs.bishopmuseum.org/pi/pdf/9(2)-175.pdf


additional papers
http://www.sea-entomologia.org/Publicaciones/RevistaIbericaAracnologia/RIA10/R10-014-149.pdf 

http://www.bio.davidson.edu/courses/invertzool/lab/ex5spiders.pdf <-- paper from an Invertebrate Biology course at Davidson University in North Carolina


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## Zoltan (Mar 19, 2012)

cacoseraph said:


> no, i'll find some of the papers i've read.  the actual workers in the field of arachnology use the terms all but interchangeably.  generally, in science, you use the terms as used by the experts in that particular field


I'd like to state that not everything published by experts is necessarily always correct, even in a peer-reviewed journal, and I don't mean hypotheses but terminology. For example, an article was published last year in a peer-reviewed journal about _Brachypelma albopilosum_. The specific name was incorrectly spelled "_albopilosa_" in the article, a person I know has e-mailed the author and told her what should be the correct spelling. The reply was that the term "_albopilosa_" corresponds to the plural of the term "_albopilosum_" in Latin, the author apparently lacking basic knowledge about scientific names. Don't you find it a bit scary that a biologist doesn't know that a name of a species doesn't have a plural form and apparently lacks very basic nomenclatural knowledge— and that this error has also gone unnoticed by the reviewers?

That being said, I am in agreement with you here regarding poisonous contra venomous. If I search Google Scholar for "spider poison", almost all of the hits on the first couple of pages are for "spider venom", also I remember I have seen venom used more times than I have seen poison. However, after a short search I have found sources which state regarding the etymology of the word venom that it actually means (or can mean) poison.


1. From the Online Dictionary of Invertebrate Zoology:
*venom* n. [Latin _venenum_, poison] The secretion of the accessory venom, or poison gland. *venomous* a.

2. From dictionary.com:
Origin: 1175–1225;  variant of Middle English _venim_  < Anglo-French; Old French _venim, venin_  < Vulgar Latin _*venīmen_,  for Latin _venēnum_  magical herb or potion, *poison* < _*wenes-nom_,  equivalent to _*wenes-_  desire ( see venerate, Venus) + _*-nom_  noun suffix

3. From Online Etymology Dictionary:
*venom* early 13c., from Anglo-Fr. and O.Fr. _venim_, from V.L. _*venimen_ (cf. It. _veleno_, Sp. _veneno_), from L. _venenum_ "*poison*," earlier (pre-classical) "drug, potion," probably originally “love potion”


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## cacoseraph (Mar 19, 2012)

most languages are always in flux (living languages).  it could be that in 50 years venom vs poison vs toxin will be very clearly defined. but at this point, i don't think we can draw a clear and definitive line between them. to make bold claims to the contrary is not really supportable, imo.  if it was only one author or only dated documents that used poison "instead" of venom that might be one thing... but it clearly is not the case here.  i have probably seen venom used more often than poison, but that doesn't mean it is the only correct term.

my main point is that it is not a bulletproof claim that venom means something other than poison. if anything, i think the strongest case can be made that venom is a subset of poison, which means poison is the broader and most often correct term, but that venom is more descriptive


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## MrCrackerpants (Jun 20, 2012)

Sorry for resurrecting an older thread but does anyone have a U.S. distribution map for the species in the Latrodectus genus? Thanks in advance.

Nevermind. I just found this free journal article that answered my questions. 

http://nature.berkeley.edu/~gillespie/Publications_files/GarbGonzGillMPE.pdf

Great read.


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## Widowman10 (Jun 21, 2012)

MrCrackerpants said:


> Sorry for resurrecting an older thread but does anyone have a U.S. distribution map for the species in the Latrodectus genus?


don't know if this is kind of what you were looking for, but here's a distribution map:
https://sites.google.com/site/widowman10/latrodectus-regions


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## MrCrackerpants (Jun 21, 2012)

Yes, this will work. Thanks!!


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## Venom (Jun 21, 2012)

There is also the state-by-state listing of known venomous spiders available here: (though it likely isn't up to date with the spreading L. geometricus).

http://www.venombyte.com/venom/spiders/venomous_spiders_by_state.asp


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## MrCrackerpants (Jun 21, 2012)

Venom said:


> There is also the state-by-state listing of known venomous spiders available here: (though it likely isn't up to date with the spreading L. geometricus).
> 
> http://www.venombyte.com/venom/spiders/venomous_spiders_by_state.asp


Thanks for this.


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## Ciphor (Jun 21, 2012)

Venom said:


> There is also the state-by-state listing of known venomous spiders available here: (though it likely isn't up to date with the spreading L. geometricus).
> 
> http://www.venombyte.com/venom/spiders/venomous_spiders_by_state.asp


"_Hobo Spider or Aggressive House Spider - Tegenaria agrestis_"

I have trouble trusting the creditability of a source that does not even know the meaning of a common latin word like agrestis (Of or pertaining to land, fields or the countryside _not_ meaning aggressive)

I'd bet this person simply google/internet searched stuff and put it together. idk, not trying to knock what you posted, just hard to trust stuff like that.

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## Venom (Jun 21, 2012)

AFAIK, the "aggressive house spider" nickname doesn't derive from "agrestis," but from alleged observations of its behavior. Supposedly it is more defensive than other Tegenaria sp. I've heard it called by that nickname frequently. The actual toxicity of T. agrestis is still debatable, of course, but this list, I think, is erring on the side of caution by including it.


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## Ciphor (Jun 21, 2012)

Venom said:


> AFAIK, the "aggressive house spider" nickname doesn't derive from "agrestis," but from alleged observations of its behavior. Supposedly it is more defensive than other Tegenaria sp. I've heard it called by that nickname frequently. The actual toxicity of T. agrestis is still debatable, of course, but this list, I think, is erring on the side of caution by including it.


Sorry, but your flat out wrong. I'll lean on the expert- Rod http://www.burkemuseum.org/spidermyth/myths/hobo.html

"Fact: Once upon a time, an entomologist who shall be nameless wanted to write about the spider Tegenaria agrestis. "Agrestis" is a Latin word meaning "rural." But this gentleman didn't know much Latin, so he coined the name "Aggressive House Spider" for the species. Arachnologists suspected that the name was intended to encourage irrational fear of spiders, for reasons it is better not to speculate on. In any case, everyone who knew anything about the species realized how inappropriate that name was."

Internet myths spun this unacceptable name out of control. 

The debate about the hobos toxicity is over. It is simply a mater of time and medical review of all the research. They are not dangerous, the venom is not medically significant.

I challenge you to find a shred of evidence to support that claim Venom... I attached the most creditable research proving the venom is harmless to vertebrates. 
	

		
			
		

		
	

View attachment Hobo toxicology (1).pdf

Reactions: Like 1


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## The Snark (Jun 21, 2012)

*Says it all*

From Ciphor's link (http://www.arachnoboards.com/ab/attachment.php?attachmentid=105144)
"Hobo Spider Venom Hemolysis Assay.
A simple test that can help determine whether or not a spider may cause medically significant bites is a hemolysis assay. Compared with the known hemolytic activity (>37%) associated with Loxosceles reclusa Gertsch and Mulaik VGH, the potential of T. agrestis VGH to cause hemolysis was negligible at 0.62 and 0.93% for male (n=5) and female (n=7) spiders, respectively."

Okay. It is harmless. Period, paragraph. My kitten was far more aggressive and the Pastuerella Multoceda it most likely carried a far greater a biohazard.

So really, the debate is now one of correct terminologies. If those involved in this discussion will please review the rules for giving an animal a proper scientific name, I believe it clearly states the name shall not be ambiguous or cause confusion. Obviously, the word Agresti, while quite scientifically proper, has caused just that.

Let us all remember, the world of science's greatest enemy is homo stultus. If there is any possible way of screwing something up, humans will do it. Or as a rather brilliant professor once remarked, Murphy's Law supersedes Ohm's.


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