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enter image description here

I was in Cobija in northern Bolivia, and these spiders were hanging around a lamp post. There were over 100 of them. The picture is not a good one, but I can describe them:

  • They were black with light blue stripes on their body, and the legs were black and yellow. They formed a big X with their legs.

Anyone know what spiders these are?

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    $\begingroup$ Read your text twice because others will read it 10-20 times, for words like spiser and picrure, it's a good forum to learn how to say things tactically without resorting to adding S on vocabularys. $\endgroup$ – com.prehensible Jan 14 '18 at 7:19
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    $\begingroup$ Those are just Argiope, a common spider. The proper identification of the species may be impossible due to the poor quality of the image. $\endgroup$ – user24284 Jan 14 '18 at 8:36
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The size, shape and leg arrangement as it hangs upside-down in the web, marks this spider as an Argiope, as previously noted. The big white band on the front of the abdomen suggests A. argentata, but the photo is blurry enough that some of those spiders might be A. trifasciata. I'd be happy to put it down as Argiope species, in the hope that more, and closer photos of this neat and completely harmless (to humans) spider are forthcoming.

Argiope argentata

https://bugguide.net/node/view/2033

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  • $\begingroup$ Again, thanks for your expertise in spiders, John, but please provide support and provide citations for images (preferably those from reputable sites that properly ID the species you include). Thanks! $\endgroup$ – theforestecologist Jan 24 '18 at 0:12
  • $\begingroup$ What’s with them hanging out in numbers like that? $\endgroup$ – Melanie Shebel Jan 31 '18 at 5:22
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    $\begingroup$ The normal reason for finding lots of relatively solitary spiders in an area is that there's lots of food there. Anywhere near a light source is a good place for flying insects, depending on the surrounding area. I've seen closely packed webs on a lighted bridge over a canal, for instance. There needs to be some sort of support structure as well, for the spiders to anchor the webs to; the photo is fuzzy enough that whatever is there is hard to see, but I would assume a wire fence or some other wire structure serves as the base that the webs are attached to at the top. $\endgroup$ – John Robinson Feb 1 '18 at 18:09
  • $\begingroup$ The interesting thing to me about this photo, and thanks for the question, Melanie, is that we would expect to see this sort of congregation around a light source for night-hunting spiders, like the usual Araneid orbweavers. Argiopes, in North America, at least, are mainly day-hunting spiders - which may be a factor in their practice of making those center stabilimenta in the webs. You wouldn't expect a light source to be all that important to spiders that operate their snares in the daytime. Perhaps something else is going on, or perhaps these spiders have learned that night is better. $\endgroup$ – John Robinson Feb 1 '18 at 18:13

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