Yellow Sac Spider

So I said at the end of my last post that I would be updating more frequently, and look at me - doing what I said I would. Nice!

If you're one of my very most extra loyal readers who eagerly awaited my bug updates even before I launched the global phenom that is BugsIRL, you may recognize this post. But keep reading - there's new content and, as always, plenty of new action/excitement!


Look at that abdomen on her! She only wears a size -50
Applebottom Jeans, but she wears them well!

Way back in early July, my wife and I were doing some Spring cleaning (in our house, "Spring" cleaning is more of a year-round activity and often involves spreadsheets). While cleaning, we had the back door open for much of the day. At one point, my wife saw a spider waltz (it was more like a tarentella, for all you many, many fans of Rennaissance Itallian folk dance) into the house like it owned the place - as if there's a sign on our house that says: Please come in and tell us about the Good News (do I intend to suggest that this spider is a Jehovah's Witness?). Anyway, my wife immediately asked me to "take care of" this spider. Being the hospitable type, I obliged and offered her a cookie and inquired as to whether she would be joining us for dinner (the spider, not my wife). Typical of the rudeness I've come to expect from Yellow Sac Spiders, her response was noncommittal.

As Yellow Sac Spiders in the US go, we have two species: Cheiracanthium mildei & Cheiracanthium inclusum - both of which are European imports (spiders are excellent hitchhikers).

While I didn't keep her around for prolonged study, the pictures I took, and her behavior, lead me to believe that this is more likely to be C. mildei, which is well known to enter homes. Whereas C. inclusum tends to stay in fields and gardens. Also, C. mildei is typically more ashen colored and often has a dark face, contrasted with C. inclusum, which is typically a lighter yellow and is less likely to have a dark face.

It's not unusual to find traces of these guys in high corners of houses. They'll do this anytime, but especially at the end of an instar (growth phase), they'll find a quiet, out of the way place, make a silky silky sac, and molt in there. When they're done, they leave their webby hammock with all their old exoskeleton in the hard-to-reach spot they chose like a bunch of freeloading jerks (Oh yeah, I'm done in there. Just clean it up whenever you get around to it. Bye-bye!).

Another awesome about Cheiracanthium Yellow Sac Spiders: their bites may have some medical significance...or not. Reports on this vary pretty widely. I've read everything from an itchy red spot to a few days of aches and nausea. Further, I came across one source that claims this to be the world's 10th most venomous spider. However, the most common report seems to be a painful but small swelling at the bite site that takes a while to go away. My personal read of the more severe reports is that a few (most likely) dry bites resulted in some mild infection, which elevated things from yucky to rather unpleasant. In addition, the one singular only report of tissue necrosis struck me as ready for debunking, aside from the reported bite having probably not come from a Yellow Sac Spider in the first place. As if the literature on Cheiracanthium toxicity wasn't all over the map enough, there's also debate about their bites, themselves. While some authors claim that Yellow Sac Spiders won't bite humans at all, even when provoked, others claim that they do bite without provocation and attribute slumber-bites to them.

Spiders have been causing people to freak out and overreact for a long time (see: tarantism & the tarantella). But Yellow Sac Spiders are also somewhat notorious for reasons other than potential (but unlikely) toxicity and have even made the news a few times. In 2011, another closely related species (C. inclusum) was in the news for making its home in 2009 & 2010 Mazda 6 fuel lines, causing loss of fuel pressure. After a few dozen complaints, Mazda recalled these two model years of the 6 to correct the issue. One source I read said that it was eventually discovered that they were entering through an opening near the gas cap and another said that they were entering through the exhaust, but I don't believe it was ever discovered conclusively why this particular species was so attracted to the fuel lines of this particular car, from these particular model years (in particular). Wikipedia simply says that they like the smell of volatiles in gasoline. I was skeptical, so I read the article that the claim cites. The citation is a Reuters article and the particular claim is a quote from someone described as an automotive journalist...That doesn't make the claim incorrect, but I don't think I need to explain the pause before this sentence. If any reader knows of a reliable source that this journalist may have been referencing, please post it in the comments.

Here's another interesting: the family (Miturgidae (older sources have them grouped in Clubionidae)) that these little darlings belong to is sometimes called the Prowling Spiders. That sounds slightly bad ass...or at least bad butt. They are so bad butt that they don't even use webs to catch their food (total Chuck Norris move) - they prowl it out! Now I skipped my hip-hop aerobics class last week to take my lady tot he new DQ Grill & Chill across the street for some soft serve, but I'm pretty sure that the "prowl it out" is a procedure associated with the pop-and-lock methods of whittling my midsection and toning my core.

Kind of like Tickle-Me Elmo...except with
fangs and gonopores (...Look it up! - Ha! Nice
Zoidberg reference.).

My conclusion on the bite stuff is that I wouldn't be too worried about it - although I probably won't be uncurling every webby leaf in my garden. Since I don't want to be liable for anyone getting pinched, I'd advise that if you're going to pick up a Yellow Sac Spider for tummy rubs, like I did in this picture, you should use the last paper towel to do it. Also, your wife should have just replaced the paper towels for you without making such a fuss.

So after some awkward small talk with the uninvited Yellow Sac Spider pictured, I politely asked her to hit that old dusty trail (notice my delicate use of the appropriate requesting-towel... light quilting maximizes request acquiescence).

I mentioned earlier that I didn't keep her around for any prolonged observation. But, in preparation for this post, I did manage to trap what I thought to be a male of this species, out in my garden. But after taking a closer look at the pictures I took of this other spider, I now believe it to be an immature female Cheiracanthium inclusum (the other Yellow Sac Spider species mentioned). So those pictures won't be a part of this post. I'm not sure yet if I'll do a post on that spider some time this winter, or if I'll just put them in an online photo library (once I finally get around to doing that). But I will be sharing them with the world, soon enough.

Everyone would start jockin', tha news would take my picta' - damn, I wish I could be a ninja!
 - The Insane Clown Posse