I thought, "This is interesting, a spider that likes the smell of gasoline. I want to know more about that." So I did some searching about the yellow sac spider. Here are some of the basic, most salient facts:
One example of the kind of Photoshopped images showing the yellow sac spider in a gas tank.
(Image from Free Republic)
None of the pages describing the yellow sac spider in & of itself said anything about the spider liking the smell of gasoline, or hydrocarbons, or hydrogen oxide.
Let me repeat that but in a slightly different way: all of the entomology/spider/species resources I checked said NOTHING about this type of spider liking the smell of gasoline.
Yellow sac spiders do have one unusual physical feature: they have 8 eyes, 2 more than most spiders have.
(Photo by Joseph Berger, from Bugwood.ord, sourced from CNNMoney)
- There are a couple types of spider that do utilize hydrocarbons:
- The males of certain very tiny dwarf spiders (linyphiids) emit a type of hydrocarbon that works sort of like a pheromone and tells females the male is fit and would make a suitable mate.
- Another type of spider called corinnids mimic the ants that they live among so they can eat the ants with impunity. These types of spiders look or walk like the ants. One species even has the mimicry down to such a science, they also emit a hydrocarbon, similar to one that the ants themselves use, which tells the ants "I am a colony-member, not an intruder." Like the yellow sac spider, corinnids build sacs. But corinnids are in the genus Castianeira, and yellow sac are in the Cheiracanthium genus.
- These are the only two types of spiders I found that have anything to do with hydrocarbons. But these are not yellow sac spiders.
The only sources I found that said anything about the yellow sac spider in particular liking the smell of gasoline, or hydrocarbons, or hydrogen oxide, were all news articles or blog posts about the Mazda recall.
Seemed pretty fishy to me. I wondered, did someone make a factually incorrect statement at some point, and everyone has just kept repeating that statement without checking it, for years?
So I started looking into some of the supposedly factual statements in the news release.
For example, you may have noticed that the AP story I quoted above (and all the others robotically following suit) says that the spiders in the Mazda gas tank are building
webs and it's the
webs that are causing problems. But, as we've learned,
yellow sac spiders do not build webs, they
build sacs.
Is it the news sources that are incorrectly describing what the spiders are doing? Maybe the original information from Mazda was more specific and accurate. So I found the recall notice.
Diagram showing Mazda's evaporative canister and other parts of the fuel system where the spider may build its home.
(Diagram from Engine-Codes.com)
- The text of the actual 2014 recall notice from Mazda says that a spider "may weave a web" in the evaporative canister vent line, causing a restriction. It says that in November 2013, Mazda "found that there was a crack in the fuel tank and a spider web was present in the canister vent line," and they found 9 cases of similar situations. Webs.
- In February 2014, they changed the way they wrote the software code that controls the fuel tank pressure to keep the tank from cracking "even under such a severe condition as the canister vent line is clogged by a spider web." Again, web.
Well, maybe Mazda are just trying to be general in their description, to use language everybody will understand, rather than to use something more specific like "spider sacs" or some such. Or maybe the thing they were seeing in the fuel line was really a web, and not a sac. So maybe this particular spider isn't really a yellow sac spider at all.
This is the thing that a yellow sac spider builds: a sac. Here, a female is tucking her eggs into it.
(Photo from Forestry Images)
So where did the assertion that this spider is a yellow sac spider come from?
- According to an LA Times article published in 2011 when Mazda issued the first recall notice, it was Mazda that identified the spider as the yellow sac:
- "Mazda identified the culprit as the yellow sac spider, or Cheiracanthium inclusum. The pale, mildly venomous creatures lay their eggs in silk-wrapped bunches — usually in vegetation. But why they're choosing Mazdas instead of, say, Porsche Spyders, is a
mystery. As is the fact that only the 4-cylinder Mazda6 cars are playing
host."
So it is definitely the yellow sac spider that is
spinning its webs building its sacs inside Mazda6 cars. I'm going to give Mazda the benefit of the doubt on this point, and say that they use the word "web" in their recall notice so as to be easily understood, when they more accurately should have said "sac."
But we still have the question that got me started on all of this: where did this business of yellow sac spiders liking the smell of gas come from? That, after all, is the
reported reputed reason why they are building their
webs sacs in the fuel lines of Mazada6s.
- In 2011, when the first recall notice was issued, USA Today actually talked to an entomologist -- not one, but two! The first one said that the yellow sac spider is very common, you often see them running around in your kitchen or basement.
- The second entomologist said that yellow sac spiders
"are found throughout the nation, and there is no particular reason
why they would choose the inside of a car body to hang out, rather than
some other crevice, says Rick Vetter, a researcher at the University of
California-Riverside."
- Nothing about liking the smell of gas. Or hydrocarbons. Or hydrogen oxide. Only that inside a fuel tank is a nice, hidden little spot like any other hidden little spot that they like for sac-building.
