Annual Brown Recluse Spider Warnings

It is almost Spring in the Northern Hemisphere. One thing this means that US citizens and I’d bet some Canadians will be receiving the annual Brown Recluse Spider Warnings via Email.

In order to reduce the negative effects of this email spamish meme, I hereby inoculate you. If you get the email, which usually comes with dire warnings and lots of photographs of bad things happening to people’s flesh allegedly because of a recluse spider bite, just delete it.

Look at this map and read the caption:

This map is based on data collected by arachnologists and is provided courtesy of Rick Vetter. Generally, recluses can be expected to be uncommon at the margins of this range. Rarely, they are found outside of this normal distribution in very localized areas. Such rare encounters should not be interpreted as a broadening of the species typical range or as an indication of large populations throughout the area in which the unusual sighting was recorded.

The recluse spider packs a nasty bite, but is not as common or widespread as the email you receive will suggest, and it is not as dangerous either. The Brown Recluse Spider Project has more.


  1. #1 Lorax
    March 11, 2010

    Bah, wussy little recluse. Its those damn Black Widows I despise. When I lived in AZ, they were fucking everywhere. Go to adjust the VCR hook up behind the TV, black widows, move a box in the garage, black widows, grab the door screen to put back in, black widows, get the odd pot from the back of the cabinet, yep black widows. Never got bit, but got too close a couple of times.

    And don’t even get me started on jumping cholla!

  2. #2 Greg Laden
    March 11, 2010

    Whagt’s fun is when the jumping Cholla and the black widows duke it out.

  3. #3 george.w
    March 11, 2010

    A friend of mine was all freaked out about the possibility of meeting a terrifying rattlesnake in Arizona. Even when informed that a snake has no interest in you other than not getting stepped on, and that a four-foot snake can only strike two feet, he was still worried.

    I’ve heard that brown recluse spiders join up with sharks and welfare queens to attack society as a whole. Better safe than sorry, I always say.

  4. #4 Doug
    March 11, 2010

    I seem to have terrible luck with spiders. Got a black widow bite once on a canoeing trip, and a brown recluse got me a couple of years ago. Of the two the recluse was worse. Both were quite painful, but (at least in my case) neither was as bad as conventional wisdom often makes them out to be. The scar from the recluse is visible, though. I guess all I need now is a tarantula bite and I’ll have the scary arachnid trifecta.

  5. #5 Lorax
    March 11, 2010


    The tarantula has to come from South America, the North American ones are not included in the trifecta. Of course nothing compares to the lethal arachnid territory PZ finds himself in atm.


    Your scenario is interesting however we all know that jumping cholla and black widows have an unholy alliance. I believe they are trying to recruit gila monsters into the axis of Sonoran evil because of its cool name and that it is 1 of the only 2 venomous lizards on the planet.

  6. #6 Hank Roberts
    March 11, 2010

    Good bit here:
    “… transported spiders virtually never establish populations after being moved, the numbers of spiders found outside the native area of the brown recluse are very few yet diagnoses of their bites are hundreds and thousand times more plentiful than are verified finds of the spiders. It shouldn’t take a math whiz to realize that the medical community is overdiagnosing brown recluse spider bites. If you truly think you were bitten by a recluse in your home, you should be able to find several specimens in a few days if you look for them. They are NOT hard to find where they prosper.”

    What’s _really_ interesting is that “spider bite” misdiagnoses are missing some real cause, likely MRSA.

    I’d guess that suggests community-acquired MRSA may be much under-reported (if it’s even being reported routinely). Any medical statisticians know more?

  7. #7 rob
    March 11, 2010

    what is the other venomous lizard? i recently read that komodo dragons are venomous. so are there three now, or is the komodo the second?

    a, a quick google search revealed the second is the Mexican Beaded Lizards. also, recently monitor lizards have been shown to be venomous (of which the komodo is one) so there are now several poisonous lizards.

    gotta google jumping cholla now too.

  8. #8 Greg Laden
    March 11, 2010

    Someday I will have to tell my favorite spider story. Its a great story, but the ending is kind of vague.

    And yes, it’s a Pygmy story.

  9. #9 Rob Jase
    March 11, 2010

    Can’t say I’ve ever run across a brown recluse but I use to come across black widows while cleaning my parent’s house’s rain gutters. I always found them to be pretty mellow & none ever even tried to bite.

  10. #10 Lorax
    March 11, 2010

    I think the evidence on komodo dragons being venomous (at least to people) is quite weak. They do carry a variety of pathogenic bacteria that themselves make toxins, but thats not the same as venom. I think there was a discovery of potential venom glands, but I dont think the discoverers ruled out other possible types of glands or glandular functions.

    By the way I dont think an 8 foot 150lb lizard with razor sharp teeth and a mouth full of septicemic bacteria has much need for venom, but I could be wrong.

  11. #11 Bruce H
    March 11, 2010

    I live in south-east Texas. I’ve run across brown recluses many, many times when doing things like changing light bulbs in outdoor lamps. Never got bit. Like most small critters, they don’t really want to bite you. In fact, they’ll go out of their way not to if you give them a chance, but will if they feel threatened. The upshot is, don’t go sticking your hands in small spaces that you haven’t looked into first.

    Really, that’s just common sense. It applies to much more than just Brown Recluse spiders.

  12. #12 Doug
    March 11, 2010

    Well, fortunately I have travel to South America on my schedule, so with any kind of luck I should achieve the trifecta by the end of the Austral winter.

    @6 — thanks for the interesting information. Maybe I’m not in the running for the trifecta after all? I live well within the red reclusa zone, though, and have confirmed the little buggers in my house.

  13. #13 bug
    March 11, 2010

    I have a 1/2 written post about the over-diagnosis of brown recluse bites…I’ll have to move that up in the queue of “things I’ll get to any day now.”

  14. #14 Jim
    March 12, 2010

    I got bitten by a brown recluse. It was hiding near the composter outside our house. My leg was weirdly tingly for a day or so, but that was about it. I removed it carefully and put it in a jar. It died about an hour later, cause unknown, but it was most definitely a recluse. A lot of people have asked why I didn’t preserve the spider for posterity so I’d have proof, but I think those people don’t realize how difficult it is to preserve a spider well.

  15. #15 Katie
    April 2, 2010

    I live in Phoenix and found a brown recluse spider in my house this fall. I had a pest control company come out to check my house because I was afraid it had laid eggs; and I did not want baby brown recluses all over my house. I really hope I never come across one again.

  16. #16 HLeavell
    July 2, 2010

    I have many in my home and by the research I have done it appears that having an exterminater come to your home to spray does very little good. I have also read that they don’t negotiate slick surfaces and that is false because I just took an item of clothing out of my dryer and there was one on it. I had gloves on thankfully. I have the sticky traps and those are fine if they happen to run through them. This is the 5th one I have killed in a 2 month period but the first I have found in my dryer, just another thing to worry about. Well I have to get my gloves back on and go find it, I sprayed insecticide directly on it about 15 minutes ago so hopefully it is dead. Oh it is true that everyone is affected differenty by their bites and some may only experience slight discomfort but there is a woman in my town who was bitten and she has had serious health problems and every years she has an erruption of the site of the bite and it has affected her major organs and that scares me! I live in Missouri.