Happy Halloween!

are-gee-OH-pee our-ON-tea-uhArgiope aurantia

Those who think scientific names are too complicated have the following dizzying array of common names to choose from for this species: black and yellow garden spider; black and yellow argiope; yellow garden spider, yellow garden argiope; yellow garden orbweaver; golden garden spider; golden argiope; golden orbweaver; writing spider; scribbler; corn spider. Or instead, just say Argiope aurantia (are-gee-OH-pee our-ON-tea-uh) – it is unambiguous and will make you sound intelligent.

Large females are commonly encountered in late summer and early fall. This fine lady was photographed 7 September 2008 at Victoria Glades Natural Area in Jefferson County, Missouri. Quite coincidentally, North America’s tarantulas (genus Aphonopelma, represented in Missouri by A. hentzi) reach their natural northeastern limit of distribution in this very glade complex, located ~30 miles south of St. Louis.

There are five North American species of Argiope, of which two occur broadly across the eastern U.S. Argiope aurantia can be distinguished from Argiope trifasciata (banded garden spider/argiope/orbweaver) by the zig-zag pattern of the stabilimentum of the former and the transversely striped abdomen and spotted legs of the latter.

Despite its name, the function of the stabilimentum (reinforced area in the middle of the web) remains controversial. The idea that it somehow adds stability to the web is not given much credence today. A visual function seems much more plausible, especially when considering that only diurnal spiders make such structures. Possibilities include camoflauge for predator avoidance, the seemingly opposite idea of increased visibility to prevent accidental destruction of the web by birds or large animals, and even prey attraction through enhanced reflection of ultraviolet light. Stabilimenta in different spider lineages probably evolved independently and may have different or even multiple functions.

22 thoughts on “Happy Halloween!

  1. Happy Halloween to you too, Ted. Great shot of the Argiope aurantia.

    It seems as if we went through a few years when seeing these spiders was almost a rare event, but the past couple of years, they have (thankfully) become numerous around our place again. I don’t have a clue as to the reason(s).

  2. I’m hopeless when it comes to knowing and remembering scientific names, and I can guarantee that a species that has no common name will not be remembered by me, beyond maybe “I think it started with an A”. I think the reason people (such as myself) find scientific names so tough is because it’s like learning another language (a lot is from Latin, so it almost is another language). Unless you know that language, basically you’re just learning random jumbles of letters with unclear pronunciations, hardly something that easily sticks in the mind. For instance, “Northern Walkingstick” is a lot easier to remember than “Diapheromera femorata“. There are some people out there who have minds that are adept at picking up and remembering stuff like that, but I’m afraid I’m not one of them.

    These spiders are among my favourite. I haven’t seen very many, which seems surprising, you’d think they’d be hard to miss. Perhaps I’m just not looking in the right spots.

  3. Personally, I think camoflauge is the most plausible explanation for the stabilimentum. Depite their large size and bold colors, my experience is that these spiders are not at all conspicuous in their habitat. Many times I have been walking along and not even noticed them directly in my path until I almost run right into them – even with my well-developed arthropod search image. Once I see them, they seem like they should be extraordinarily visible, but I believe the stabilimentum somehow disrupts their silhouette. If this is true, then they may be much more common than they appear to be.

    Seabrooke – a lady as intelligent as you (IMHO, based on your fine writings) cannot be hopeless. Latin is the language of science, and anyone interested in science will, by default, learn basic latinized terms through osmosis. I must confess that I was being a little flippant in my comment about common names, but the problem with them is not insignificant. If I may use the example you provided – yes, there is little chance of ambiguity as to what you are talking about when you say “northern walkingstick.” But “common walkingstick” is another common name that has not only been used for this particular species, but also for the genus Diapheromera as a whole as well as the entire family (Diapheromeridae) to which it belongs. Other variations on these common names also exist – e.g., common American walkingstick and northern stick insect. When you consider an increasingly international readership, you can see the potential magnitude of the problem. Of course, these ambiguities can be resolved by common name conventions, as has been done with most higher vertebrates and even a few popular insects groups such as butterflies and tiger beetles. The vast majority of invertebrate groups, however, have not been the subject of such naming conventions – in their case, scientific names are clearly preferred. I’m really not against common names – you’ll note that I indicate common names often in my posts, but always associated with a scientific name (except for Rich and Chris).

  4. What a great post once again, and great photo. Spiders in this group seem very common, but aren’t always noticed until the web is in your face. Then you see them all around you! Maybe there is a sort of ‘invisibility cloak’ effect that these webs have that is very effective for catching small flying creatures (and making humans say “ugh!”).

    Re using scientific names, once you get accustomed to using them, they become second nature. I found that an easy way to learn them was by typing up lists. Something about the action of typing and paying attention to the letters makes the name easier to remember for me.

    It’s best to work from scientific names to prevent confusion about which species is being referred to, and because so many invertebrates don’t have common names it’s often the only way to refer to them. A lot of the language in science is more about familiarity than difficulty.

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    • Like anything, it can bite if you carelessly try to handle it. Otherwise they are supremely non-aggressive and eat other insects that could be munching on plants in your garden. I would welcome its presence and enjoy its beauty.

  6. Interresting… we just found one this morning in our plants. Of course her size scares us, but if you say she’s non agressive then we’ll just let her be. Never seen anything like it before. We’re in San Diego, Ca.

  7. Villa in Mercia Spain and there are two of these outstanding specimens on the foliage next to our pool one obviously female much bigger than her smaller male neighbour.

    • I suggest they might be the related species Argiope bruennichi, which occurs in Europe and northern Africa and is very similar in appearance to the North American A. aurantia.

  8. Thanks for the great post, My husband and I just got in from running errands. This beauty, found her a bee and we actually watched her tie him up.. Immediately looking this rare spider up.. and stumbled across your post! Glad to know its harmless. I’m still going to grab a broom.. and place it back in the woods 😉

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  10. ONe off my deck this morning was making the stabilementum vibrate rapidly back and forth. Once I saw it and walked closer it stopped and just sat there. I tried to take a video of it doing that but it wouldn’t repeat its performance once I was that close. Perhaps the movement attracts its prey to come take a closer look just like I did?

    • I have noticed that when many spiders I’ve stumbled across are actually weaving their web it does seem to vibrate because of the intense speed of their legs when doing so .. not sure of that is what you witnessed or not? Maybe she was still weaving her web and stilled out of nervousness when you approached or maybe it is what like you said and was trying to attract? Hmm..

  11. I have one of these on my porch, I am quite frightened though! I have 2 children, is it poisonous? It is quite large and I’ve never seen a spider like this before!!

  12. I’m from Waterloo Ontario and have a photo of one of these spiders that was webbing on our front door, if you give me an email address I will forward the photo.


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