Most venmous spider of North America.

[Twillis10]

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.

 

[BigJ999]

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.

 

[Ciphor]

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)

 

[Venom]

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

 

[Ciphor]

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.

 

[MrCrackerpants]

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

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?

 

[Richard McJimsey]

Does anyone have a distribution map for the Latrodectus genus?

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

 

[loxoscelesfear]

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

 

[The Snark]

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

 

[MrCrackerpants]

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

 

[Ciphor]

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

 

[The Snark]

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

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.

 

[Ciphor]

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.

 

[John Apple]

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

 

[John Koerner]

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.

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

 

[Widowman10]

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.

 

[OBT1]

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

 

[Jared781]

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

 

[Ciphor]

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

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.

 

[Venom]

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.