Friday, May 14, 2010

Long-Legged Sac Spider



  Long-Legged Sac Spiders in the genus Cheiracanthium are easily recognized by their long front legs and their overall "long-legged" appearance.There are 400 species within the family Muturgidae that are found worldwide. There are approximately 50 genera within Cheiracanthium. In the United States there are two species; "Yellow-Sac Spider" (Cheiracanthium inclusum)is the only species indigenous to the United States and is the most wide spread and can be found throughout most of the United States with exception the northern most states. Another species C. mildei is an introduced species, and originally came from Europe. In the late 1970's it was found throughout most of the northeastern United States. Most likely it's range has increased substantially since then. The yellow-Sac spider is about the size of a nickel and has a beige or yellow abdomen. They have very dark eyes and mouth.Their legs are very long, especially the front legs. It is these long legs that has earned them their common name of Long-legged sac spider.


 The yellow-sac spider is often found in homes and is the spider most responsible for household spider bites. There is some indication that they are mildly venomous to humans. The bite is reported to feel much like the sting of a hornet, and causes intense itching and burning at the bite site. In persons sensitive to the venom the reaction may be much like the reaction you would have to a black widow, only less severe. These symptoms may include fever, nausea, intense pain at the bite site, muscle cramps and malaise. Once again though, this would be a severe reaction, certainly not the normal reaction to a bite of this spider.
There is one species in Europe that is reported to cause necrosis of the skin much like a brown recluse can. There are no reports of such reactions to the Yellow-Sac Spider that calls the US home. These spiders are wandering spiders and frequently hunt for the food rather than capturing it in a web. It is during these hunting trips that bites to humans occur. The spider somehow becomes lodged between our skin and the bed sheets, clothing, etc. Of the two species C. mildei is the most aggressive and has been observed biting without provocation. C. inclusum is more often encountered in gardens where bites occur while we are moving wood piles,  planting or pulling weeds.

This particular spider pictured here was brought into my work by a woman who was concerned it could be a brown recluse as she has these spiders all over her house. I assured her it wasn't a recluse, and that while I wasn't exactly sure what it was I would find out for her. After doing some research I was able to let her know exactly what it is that has taken up residence in her home. 

These spider are also found under leaf litter, under the bark of trees,and stones. Lumber left outside will also attract these spiders. They build a web that looks like a tube or "sac" that can be found in the corners of our homes, cellars, basements, garages as well as outside. These are small webs that they are capable of building in about 10 minutes. These webs may go unnoticed on neutral colored walls. The Yellow-Sac spider is less likely to use your home as an incubation site, and seems to prefer to lay her eggs outside under leaf litter or bark. The species C. mildei almost exclusively lays her eggs within human structures.

The female will lay her eggs in the late spring or early summer. These eggs are in a loosely woven silken sac and guarded by the female. The young remain in the web for a short period of time and will eventually leave to hunt at night. They return to the safety and security of their nursery web. After shedding their skin a time or two they will finally head out on their own. They will crawl to the top of a stem or stick and let down a strand of silk and "balloon" themselves to another location. The female is capable of having a second brood of eggs several weeks after the first.


There have been studies done on their color reaction to the food that they eat. Those that consumed green caterpillars for instance took on a more greenish tint. Those fed red fruit flies, were noticeably reddish-pink in color. Still others were fed common house flies and took on a definite gray tone. 

These spiders are very rapid runners and can climb any surface without trouble. This one was quite intimidating as I took pictures of it, he ran "at me" very quickly, and relentlessly. I have an admitted phobia of spiders, and fast spiders are the worst. I am slowly overcoming my fear, but this spider could regress me!


references:
http://ento.psu.edu/extension/factsheets/agrarian-sac-spider
http://extension.usu.edu/files/publications/factsheet/yellow-sac-spiders08.pdf

18 comments:

  1. My house in infested with these!!! I am so glad I know what kind they are now!!!

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  2. i have one as a pet

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  3. I just killed one that scared the bejesus out of me in Kent Washington. I am in a hotel and was not sure what the hell it was. It had a definite yellow abdomen and a greenish head and dark eyes. Super long legs and literally climbed all over the kitchen. I was going to close the Tea Bag Box when my hand almost was touching it. Freaked me out then I tried to picture it to figure out later what it was. The legs were a dark brown though not light. Everything else looks similar. Thank god for this website. I just wanted to make sure I could sleep or if I needed to dig in for an all night fight.

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  4. Ah!
    I recently caught a rather large female!
    She started weaving a rather large web inside of the enclosure I've given her....
    I will attempt to feed her now D:

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  5. This was helpful. Thank you.

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  6. I also thought tht rhese where a brown re luse spider because of the brown spot on the back part. Still a bit freaked out though!

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  7. I moved into a new apartment and on day 1 noticed a few of these spiders I killed them and thought nothing of it . I have been there over a year and I now kill at-least 2 spiders a day. A DAY! I have a great fear of spiders and they make it worse because they run toward you instead of away from you. Just this morning there was one on my bathroom sink and when I turned the light on he literally ran toward me, like he was on a mission to freak me out. I don't know what to do to get rid of them, I have tried cleaning up and keeping surfaces free of paper or clutter, I have tried poison nothing seems to work :( please help they are taking over!

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    1. Thank you for responding to this blog post. I must say I am sorry you are feeling overwhelmed by your spider house guests. I know it can be a bit daunting to put up with them when you are phobic about their presence. I wish I had an easy answer for you, but unfortunately I don't . If you've tried chemicals, and they are still present, then they obviously aren't responding the poison. Many spiders have to be directly touched by the poison itself for it to kill them, the residual will not affect spiders at all. Brown Recluses are one example of this. I know people who use glue traps, but I am vehemently opposed to them. Often little snakes and other animals can become caught in those traps and they are very inhumane. Your only option at this point, if you are truly seeing two or more a day, is to call a pest control agent and see what they recommend. I'd tell you to try and live with them, but I know that is asking too much, so I will wish you luck instead. :o)

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  8. I live in Preston Connecticut, in a very wooded area. I have seen a few of these spiders and they scare me so much!!! There was one crawling up our wall. Do these spiders have a small body with really really long legs? Because I see a lot of comments about these spiders being small. But I see these spiders that look just like these pictures bot with the legs, their size seems sooooo much bigger. I am desperately trying to find out exactly what kind of spider this is. It is a very light brown tan color.... Ling legs, small body size, very fast. Any input?

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    1. Without seeing a picture of your actual spider it would be very difficult for me say what species it is. Is there anyway you can take a picture of one and send it to me? I would sure do my nest to ID it for you. My email is MOpiggys@aol.com

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  9. Hi, I am concerned about a spider I found tonight in my house and am trying to determine if it's a brown recluse or long-legged sac spider or something else. I am going to send you an email with the image if that is ok.

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  10. I was recently bit by one.what should I be aware of?....HELP!

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  11. I was recently bit by one.what should I be aware of?....HELP!

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  12. My room is full of them. They crawl into my bed if I sleep in here.

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  13. It was like 12: 10 and I found this spider crawl up my leg and onto my hand and I thought I peed myself and trapped it in a cup in till I found d this website and it helped me a lot because I went to kill it and it ran away to fast but I don't get it my room is so clean and tidy and this is the only spider I've seen. I'm not really afraid of spider like I love some spiders but when I don't know ow what they are I get scared thank goodness for this site

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  14. It was like 12: 10 and I found this spider crawl up my leg and onto my hand and I thought I peed myself and trapped it in a cup in till I found d this website and it helped me a lot because I went to kill it and it ran away to fast but I don't get it my room is so clean and tidy and this is the only spider I've seen. I'm not really afraid of spider like I love some spiders but when I don't know ow what they are I get scared thank goodness for this site

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  15. I have several of their webs in the upper corners of my both my covered porches. Until tonight when I caught one on my backdoor (on the outside) I hadn't a clue what spider was making them.
    I'm in eastern Washington and as we have black widows,hobos, wolf spiders AND Brown recluse..well I thought it best to capture and investigate due to its large round body despite it being the wrong color for a black widow.

    (I once picked up an albino b.widow that had been temporarily paralyzed by a blue wasp not knowing what it was initially..oopsie��)

    While I have been enjoying watching it build a quick web in the pill bottle I caught it in, I plan to release it. They are very beneficial house spiders as they keep the pesky bugs out of my house..well..beneficial to me as long as they stay outside that is ��.I'm not quite generous enough to share my indoor spaces with them.

    I'm a catch and release kind of woman though as long as it doesn't fall into the four spiders of fuckery we have here in Eastern Washington��.
    Those suckers unfortunately must be executed on sight.��

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