The Truth About The Brown Recluse Spider

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Everything you thought you knew about Brown Recluse Spiders is wrong. There is now a book,The Brown Recluse Spider, to set you straight. This is my review of that book.

His name was Bob. I was a kid, he was an adult that all the other adults seemed to think was cool. He used to have a job launching nuclear missiles for the Air Force, but then later got a job as a Hippie. He, another person or two, and I were sitting on a rock pile out in the woods, checking out the patch of marijuana planted, mysteriously, on the neighbor’s property. The neighbor was the head of the local John Birch Society. Whoever planted the patch of pot figured it would be better found, if ever found by the cops, on his property than on the property occupied by the hippies.

Somebody moved a rock. Bob said, “Oh, look, a Brown Recluse spider. They are deadly, but they hardly ever bite.”

I watched the Brown Recluse spider very carefully for a while and memorized it. I found many more over that summer, and in subsequent years. I became very good at identifying them.

This is what it looked like:

The rock pile harboring the “Brown Recluse” was many hundreds of miles away from the natural range of the Brown Recluse. And of course it wasn’t a Brown Recluse spider. Brown Recluse have been known to take up residence in buildings very far away from their home range, but very rarely. They are not found out in the wild outside of their natural range very often. I think Bob said something about running into these things all the time at the secret nuclear missile base, which was secretly hidden in Wyoming. There are no Brown Recluse spiders in Wyoming, either.

I’m making Bob sound like some kind of idiot. He was not, he was a very smart guy. But he had this wrong and so does everybody else on the planet, it seems.

A study was done about ten years ago to see how bad people were at identifying Brown Recluse spiders. People, focusing on people who should know or claimed to know, were asked to send in their spiders. Brown Recluse spiders were submitted from 49 of the US states and from Canada. They exist, however, in only 17 states and not at all in Canada. There is a spider that lives in California, a very common house spider that had never been properly studied. It does look a bit like a Brown Recluse. So many of those were sent in (California is NOT one of the 17 states Brown Recluse spiders live in) that spider experts were able to use the collection of those spiders, not Brown Recluse but some other species, to do the first major study of its anatomy.

Most of the things people mistake for Brown Recluse spiders are spiders that don’t look much like a Brown Recluse, like the wolf spider depicted above. Many of the submissions from the aforementioned study, and many of the “Brown Recluse” routinely submitted to spider experts by concerned citizens, are not even spiders. There are a few spiders that look like them, but really, it is not hard to learn the difference between the Brown Recluse and its close relatives and all other spiders. But to do so you need some expert training, and that can be attained, if you are attentive, with Richard Vetter‘s new book, The Brown Recluse Spider.

You have probably gotten the email at some point in time. Brown Recluse Spider Season is starting. They are very dangerous. They can kill you. Be afraid, be very afraid. And let’s show you some picture of children with giant patches of rotting and missing body parts or holes in their arms because they were bit by Brown Recluse Spiders, etc.

Vetter’s book is full of information on the Brown Recluse. Vetter is careful to define terms and to not speak over the heads of the average person who is not a spider expert, but at the same time, the work promises to become the standing monograph on this type of spider. It is authoritative and comprehensive where prior study allows, and as such, also points out where there may be excellent research opportunities for up and coming scientists.

I was interested to learn that the majority of behavioral and physiological work done with spiders is done with captive beasts. I believe that is generally the case with invertebrates. But the conditions of captive life dramatically alter key life history variables. More field study needs to be done of spiders, but the difficulties would be significant. It would probably bad for your back and knees. But as an experienced archaeologist, I have no sympathy. Get out there and start collecting field data, you guyz!

The Brown Recluse is one of many related species in the same genus, and the larger family of these spiders is found in both the old and new world. The taxonomy has an interesting and elaborate history, with much renaming and shifting around of phylogenetic position.

Brown Recluse eat mainly invertebrates. They don’t build much in the way of webs, and don’t really use webs to capture prey. They either hang around waiting for something to come along, then possibly attack it, or prowl.

The dispersal patterns of Brown Recluse are very interesting. They may become very common locally, but not found nearby that locality. And by locality, I mean a single outbuilding on a farm, where they are common, not to be found in other outbuildings. That is a very small scale concentration of population. Studies looking at spider dispersal have found that some species of spiders disperse great distances, including those that use a strand of web to fly as much as thousands of feet into the air, presumably traveling great distances. Brown Recluse don’t do that.

The native range of the Brown Recluse and closely related species includes a small part of California, Arizona and New Mexico, all of Texas, Oklahoma, Kansas, southern Illinois and Indiana, most of Kentucky and Tennessee, Western Georgia, and all the areas I just circumscribed with a circle of states such as Mississippi, Alabama, Louisiana, Arkansas and Missouri. The Brown Recluse itself, however, Loxosceles reclusa, is mainly restricted to Texas north to southern Illinois and east to Kentucky and Tennessee. Oh, and a tiny bit of the Florida Panhandle.

Here is how you pronounce the latin binomial. Say “Isosceles” like in the triangle. Not say it neat, without “ice,” and lock it down with a “Lox” in front. I imagine scholars differ on REEclusa vs. RAYclusa.

According to Vetter, “Outside of its native range, the brown recluse spider is rarely found….In comparison, to find forty buildings populated by brown recluse spiders in Kansas or Missouri, one would have to walk down just one residential street.”

Vetter makes two very important points about this spider that you need to understand.

First, many, many Brown Recluse spider bites, serious afflictions that are treated as spider bites, are not Brown Recluse spider bites. The misdiagnosis is generally done by a professional medical worker, and often in conduction with someone identifying a spider as a Brown Recluse incorrectly. There are other medical afflictions, including other bites but also things that are not even invertebrate caused, that are mistaken for bites of these shy spiders. That can lead to serious negative consequences for the patient. Also, for any invertebrates living in the area along with any one who breaths in the anti spider gas and juices that may be liberally spread around to kill a spider that does not exist locally.

The second is that we actually know too little about the physiology of the Brown Recluse spider bite, and need to know more. Vetter has a whole chapter on this.

The bottom line is that Brown Recluse spiders are extremely common in some areas but hardly ever bite anyone, and totally absent from vast areas where they are blamed, incorrectly, for the occasional lesion.

There are definitely dangerous spiders, and the Brown Recluse is one of them. But the human reaction to spiders in general, and even to the species that do have a nasty bite, is almost always overblown, as least in Western culture.

I believe that the vast majority of “spider bites” people get are not spider bites. Here’s why. The ideal mosquito bite involves the mosquito getting her proboscis deep into your skin, hitting a blood vessel, and withdrawing a good meal of blood. That takes a long time and is often not successful. The unsuccessful “bites” may leave a mark and be itchy, and that is what most people think of as a mosquito bite. But a successful bite will generally leave a welt, large, red, painful, itchy, and that stays around for a few days. When people get those, they call them spider bites. Why? Because most people simply don’t know what a real mosquito bite is, and think spiders bite them all the time.

That is why The Brown Recluse Spider by Vetter is a great book. It is clear, well written, authoritative, and you can’t help but be much better informed by reading it. If you live in Brown Recluse land (see map above) you need this book now, just go get it. If you don’t, and you are into inverts, science, or anything related, you’d enjoy it as well. Great book, highly recommended.

Have you read the breakthrough novel of the year? When you are done with that, try:

In Search of Sungudogo by Greg Laden, now in Kindle or Paperback
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12 thoughts on “The Truth About The Brown Recluse Spider

  1. Arachnids… way to open a can of annelids…

    In Australia the equivalent to Loxosceles reclusa is probably the white tailed spider, Lampona cylindrata (there’s also Lampona murina). White tails are famously associated with arachnogenic necrosis, which has been repeatedly debunked in the medical literature.

    Which is mildly surprise to me, because my mother was bitten by a white tail (she kept it and had its identity confirmed), and over the coming days observed the bite to swell and then become inflamed and apparently infected from the point of envenomation. The response developed into an ucler that expanded at a rate of about a millimetre per day for a few weeks, and the ulcer lasted several months.

    The classic targets for arachnophobes in Australia are the funnelweb (which is nastily venomous), red-backs (also nasty) and the family of huntsmen spiders, which are not deadly. Some huntsmen at least do pack a punch though, as I found out once when I pulled a bedsheet up to my armpit one summer night and pushed a lurking huntsman into my armpit, whereupon it bit me – unsurprisingly. The bite is like that of a wasp and it itched for about a fortnight, as well as leaving a purple network of veins in my armpit that resembled something from a zombie movie. Generally huntsmen are peacable spiders, and with skill they can be handled without gloves. They’re super fast however – I’m sure that a search engine would reveal more than one scuttling about at a rapid rate of knots.

    One of my Australian favourite spiders though (aside from the crab spiders – what’s not to love?) is the net-casting spider (Deinopis subrufa and relatives). A quick search for them using one’s favourite engine will soon reveal their wonderful skills.

    1. Thanks for this post Greg and follow up Bernard,.

      If you care to locate me on Facebook (my profile image is of myself standing behinf the tail fin of a Tiger Moth biplane) I have pictures up of some of the tarantula that I look after for a grandson whilst he is at Uni.

      I have recently worked out an escape proof way of securing a shower room, requiring some carpentry to make blanking pieces to stop them vanishing behind a sink and cupboard unit) so that any Poecilotheria regalis that escape whilst moving to a fresh home do not cause my wife to vacate home. These things are quite venomous, can run fast and jump.

  2. As a coda to the subject of huntsmen spiders, they can be incredibly beautiful animals. The species that bit me was a wonderful amber-red-brown colour, and I’ve seen some that are various shades of almost luminescent leaf green.

    I suspect that I’ve spied more than a couple of unidentified species but at the time I was not set up to record information and I was loathe to collect (= kill) for a maybe, so they lived out the spans of their natural lives in the wild…


  3. I have seen two species of Loxosceles, one of which was the brown recluse (L. reclusa) when I was in Arkansas and Oklahoma (the other was the Mediterranean recluse in Portugal). The six eyes, characteristic is sciarids, and the violin on the carapace were diagnostic. I was actually quite delighted to see my first brown recluses when I drove from the east coast of the US to the west coast in 2001. They were inside motels. I also had the pleasure of seeing two species of widow spiders, Latrodectus variolus in Oklahoma and L. hesperus in California. But heck, I am an entomologist.

  4. By the way, for Bernard, the giant recluse, Loxosceles laeta, has been introduced from South America into Australia. It is also apparently established in California…

  5. I have suddenly found myself the custodian of 29 tarantula of 24 different species, some quite large, size of a hand.

    A grandson into zoology has collected these and has now decided to go on a world tour.

    Sadly his large Mexican Red Knee (Brachypelma hamorii) died during a failed molt.

    Larger individuals are of:

    Brachypelma vagans

    Aphonopelma seemanni this is the largest

    Nhandu chromatus

    Brachypelma albopilosum

    Psalmopoeus pulcher

    Lasiodora parahybana

  6. Discovered an example of a Western conifer seed bug, Leptoglossus occidentalis, clinging to a curtain indoors last year (Southern England). I took a photo’ of it not having seen one previously.

    It appears that this has become established in the UK since about 2007.

  7. It stood out to me when you mentioned that brown recluses are dangerous spiders. Is killing a brown recluse spider the best way to deal with it? It could be a good idea to talk with an exterminator if you live in an area that has a lot of dangerous spiders.

  8. This site is doing a disservice…the Brown Recluse Spider is NOW FOUND in California..this info given is not safe and should be taken down or revised….!!!!!!!!

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