Loxosceles Reclusa (Brown Recluse)

Sure, we have black widows by the millions here in Colorado, but if you want to get your arachnophobia really humming there is nothing that does the job better than the brown recluse. The fact that this guy doesn't look particularly ominous makes it all the more fantastic. They could easily go un-noticed in your house until ** BAM **, your God-damn arm is rotting off. I once knew a girl who was bit by one on her waist and it looked as if someone took and ice cream scoup to her. Naaasty.

from Wikipedia:

The brown recluse spider is a venomous spider, Loxosceles reclusa, of the family Sicariidae (formerly of the family Loxoscelidae). It is usually between 1/4 and 3/4 inch (6.4-19.1mm) but may grow larger. It is brown and usually has markings on the dorsal side of its thorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider resulting in the nickname "fiddleback spider" or "violin spider". Coloring varies from light tan to brown and the violin marking may not be visible. Since the "violin pattern" is not diagnostic, it is far more important, for purposes of identification, to examine the eyes. Contrary to most spiders, which have 8 eyes, recluse spiders have 6 eyes arranged in pairs (dyads) with one median pair and 2 lateral pairs. Only a few other spiders have 3 pairs of eyes arranged this way (e.g., scytodids), and recluses can be distinguished from these as recluse abdomens have no coloration pattern nor do their legs, which also lack spines.

....

As indicated by its name, this spider is not aggressive and usually bites only when pressed against human skin, such as when putting on an article of clothing. Actual brown recluse bites are rare and few. The initial bite frequently cannot be felt. Most bites are minor with no necrosis, but a small number produce severe dermonecrotic lesions or even systemic conditions (viscerocutaneous loxoscelism) with occasional fatalities. (For a comparison of the toxicity of several kinds of spider bites, see the list of spiders having medically significant venom.)
The serious bites form a necrotising ulcer that destroys soft tissue and may take months and very rarely years to heal, leaving deep scars. The damaged tissue will become gangrenous and eventually slough away. Initially there may be no pain from a bite, but over time the wound may grow to as large as 10 inches (25 cm) in extreme cases. Bites may take up to seven hours to cause visible damage; more serious systemic effects may occur before this time, as venom of any kind spreads throughout the body in minutes.

Comments

[Zen]

Well, okay... Striking fear in the hearts of your readers, are we?

It's not really **BAM**! The photos you show are pictures of people who are on like step #14 of ignoring all the signs. Brown recluse bites are very treatable, and you have plenty of time before your arm rots off... even in the event that the bite you suffered is of the most serious nature.

BTW -- For those who are wondering, there are no brown recluse spiders in Colorado. From the University of CA at Riverside Entolology Dept comes the following range map of the genus Loxosceles spiders (aka recluses) in the United States...

http://spiders.ucr.edu/images/colorloxmap.gif

[pete]

I hope all of what you're saying is true, Zen. I've heard a lot of people say there are some in Colorado. And check out the pics from this guy's story. After 3 days he's got a big chunk missing from his leg.

[Zen]

Yea, but from what I understand, pete, this type of reaction to the bite is very rare. There's always going to be a minority that's more susceptible to the venom or doesn't respond well to treatment. But most will.

Even so, while the ulcer might look ghastly it is a very rare case indeed where the ulceration cannot ultimately be successfully controlled at some point. And while cosmetic damage might remain, with reasonable medical care, permanent debilatation or loss of life is very very rare.

It's kind of like worrying about scraping your knee and picking up flesh eating bacteria. Yea, it happens, but if you take proper care of the wound - wash it out, monitor it, see a doctor if conditions worsen - odds are you'll live to see another day.

http://www.uky.edu/Ag/Entomology/entfacts/struct/ef631.htm

(great pics and information on the spider itself and its bite)

[Grinth]

I am spending a couple of months in Sydney, Australia. Over here the brown recluse pales in comparison to the funnel web tarantula. Here is the wikipedia link: http://en.wikipedia.org/wiki/Venomous_funnel-web_tarantula

These things pack a punch and the males are fairly agressive. Luckily I haven't had the misfortune of meeting one yet...

[ohwilleke]

Brown recluse spiders are rare in Colorado, but not unheard of. I personally know two people in Denver who were bitten within the last year, probably in Capitol Hill, by this type of spider and hospitalized as a result (the injury from this type of venom, as the pictures and text indicate, is quite distinctive). I know of another person bitten by a brown recluse in Greeley and hospitalized as a result.

I'm not the only one who is aware of the distinctive necrotizing bites outside the range where they are most commonly found.

I would agree that the largest share of reculses are within the range shown on the map, maybe 90% (although I believe that the supporting data for the map actually says closer to 50%). But, they are occassionaly found elsewhere.

Also, outside the range, one of the problems bite victims face is that an initial misdiagnosis, and as a result, an initial mistreatment, is common.

[Zen]

It is true that non-native species do enter our state and nation all the time via transport container, shipping boxes, ballast water, etc. But most fail to find a foothold. I too know people in both Colorado and California that were diagnosed as being bitten by Loxosceles relusa, and treated accordingly. But it's highly doubtful that the species (much less the genus or even the phylum) identification was correct.

There are many types of spiders, insects, even bacteria that are capable of causing necrosis. But it is the brown recluse that routinely gets the blame. And since treatment for all these necroses is generally the same - antibiotics, tissue excision - people tend to believe that if the treament works, the species identification must have been correct. But that is simply not true.

Take, for example, the Hobo Spider - Tegenaria agrestis - also known as the Aggressive House Spider, a funnel weaver which was introduced to Vancouver Island, Canada in the early 20th century from Europe, and has spread throughout the Northwestern United States. It too causes necrotic arachnidism, and even death, when the envenomation or individual reaction is severe.

For much of the 20th century, it's bite was misdiagnosed by the vast majority of medical professionals as the bite of the brown recluse, a spider that doesn't even exist within 500 miles of the range of the Hobo. Entomologists knew this, but since the prescribed medical treament for a brown recluse bite had always worked, no one in the medical profession bothered to question the matter further.

The point here is this -- Just because you think its the bite of the brown recluse, and the standard treatment for the bite of the brown recluse works doesn't mean you were bitten by a brown recluse.

Unless you capture the offending spider, and a knowledgable party makes a positive identification (and the brown recluse is not that easy for a layman to identify), if you are well outside the known range of the species -- as we in Colorado are -- then we must assume until proven otherwise that the bite is not the bite of the brown recluse. To assume otherwise is scientifically irresponsible.

[Non-Prophet]

The girl I knew who was bit lived in Denver at the time and it was diagnosed as a brown recluse bite. She's the one with scoup taken out of her hip.

[Zen]

Did she capture the spider and have it examined by a expert? That's the only way to make a positive identification.

------->>

The following is from the Denver Musueum of Nature & Science Colorado Spider Survey FAQ. The Colorado Spider Survey is an ongoing research project committed to developing a more complete and up to date database of Colorado arachnids. To date, volunteers have sent in more than 26,000 specimins and to my knowledge, NONE have been a brown recluse.

Question: Are brown recluse spiders the most dangerous spider to humans found in Colorado?

Answer: Absolutely not! Colorado is not part of the natural range of this spider. Although single specimens are sometimes brought into the state, natural populations are not found in Colorado.

The brown recluse is the common name for the species Loxosceles reclusa. All species in the genus Loxosceles have venom that can cause necrotic lesions in humans. However, as with the majority of spiders, brown recluse spiders bite humans only when seriously provoked. Get much more information about the recluse spiders here.

Question: Brown recluse spiders must be in Colorado because a doctor said that the nasty wound on the arm/leg/body of my brother/mother/sister/uncle/friend must have been caused by a brown recluse and doctors are never wrong, are they?

Answer: Here in Colorado, brown recluse envenomization is the least likely explanation for the nasty necrotic lesion on the arm of your friend or relative and the physician in question needs to explore other causes. Whereas brown recluse bites are very difficult to treat or cure, many of the other causes of necrotic lesions can be readily treated if they are properly diagnosed early. Please see the following Web site for some of the other conditions that can cause necrotic lesions often mistaken for brown recluse bites.

[Non-Prophet]

Wow. Nice work Zen.

[darksandal]

My dad got bit by a brown recluse on his inner thigh while putting on his jeans. He was in Oklahoma visiting his parents, and was struggling to tell his mother he had HIV/AIDS. In the confusion of the spider bite he ended leaving his AZT in the guest bathroom at her house and she later took the meds to her doctor and asked what they were. And the moral of the story is .... Wear condoms and shake out your pants before you get dressed every morning. Good post, NP.

[Billychic]

During the time I lived in Mississippi and St. Louis, I came across a few spiders (was not bitten, thankfully) that were pointed out to me as Brown Recluse by supposed authorities (they may not have known a BR Spider if it came up and bit them on the ass, but they sounded like they knew what they were talking about) who enjoyed my reaction - which was to flee in terror.

Now, in NYC, I had never worried about the little harmless spiders that I have seen, thinking they were no big deal...and then heard recently that BR Spiders have made their way up north along the east coast - and work with a woman whose son's leg had a big chunk rotted out from a bite. However, I doubt that they caught the offending arachnid, so it could be a case of mistaken identity...

Your pictures and their story are not making it any easier to sleep.

Is that Hobo Spider only on the west coast? *sigh*

[Zen]

Hobos are mainly in the Northwest and Western Canada. And on trains. :0)

But they are SLOWLY spreading. Since the 1930s, they have spread to Utah and to central Alberta. It is predicted that they will eventually spread throughout most of North America with the exception of the arctic north, and our southern deserts (they like it moist and cool).

But Western Europeans have coexisted with Hobos for millenia. They're not a big problem. They are a big spider, but that isn't necessarily bad cause you can see 'em coming. :0)

In truth, Hobo Spiders like the vast majority of spiders are shy. They don't bite unless you "bite".

For more info and photos, check out http://hobospider.org.

[tina stanley]

the brown reclusa is in colorado i live in rockyford colorado and was bit by on in my house we have lots of them!!!

[tina stanley]

the brown reclusa is in colorado i live in rockyford colorado and was bit by on in my house we have lots of them!!!

[pete]

Sorry Tina,

"For those who are wondering, there are no brown recluse spiders in Colorado." - Zen

Zen knows EVERYTHING.

[Zen]

Just referencing the work of the arachnologists and entomologists of the world, pete.

:0)

I do know EVERYTHING. I also know NOTHING. They go hand in hand on the middle path.

[That girl]

gross but need more pictures

[calypsogrower]

I had some sort of arachnid chomp on me in a very sensitve place...hours later I noticed a walnut size swelling with necrosis. Four out of five of my herbal medicine books said make a squished up poultice of plantain leaves. Plantain if a lowgrowing ditchweed with parrallel veins. I mooshed the leaves with the back of a spoon until the juice was flowing. put this on gauze and applied to the now throbbing and scary bite.I gotta tell ya, it worked overnight. Swelling and necrosis gone. It can be used with any medical regime and I swear by it!

wooohoooo i like dead peaple >8)

[Raina]

Great post- but I think someone needs to re-evaluate the numbers on this spider....I caught my son (2 years old) trying to kill a B.R. with his toy cars--So i captured the nasty thing, and yep- 6 eyes, and violin present- the little bastard even 'flared' at me. I have since used Ortho barrier on my home, and I'm praying its a single occurance. (BTW- I'm in the Colorado Springs area)

[8Legger]

Its funny that I found this site while researching Urban Myths. Nice pictures, the thumb guy has been around for years. Gas gangrene is what he has, not a spider bite.

[chris]

dude thats gross

[chris]

that is discusting u can see the bone.!!!!!!!!!!!!!!

PEOPLE IN COLORADO ARE FUCKING IDIOTS,DO TTO LACK OF OXYGEN TO THE BRAIN MILE HIGH CITY FUCK OFF