Big Burrowing Wolf Spider with Babies
Pretty much every summer, we get together with a large group of friends at a site up north of here (which some of them own), that is covered with about 160 acres of “stamp sand”[1]. In 2014, this event occurred on July 5. While we were there, a group of people setting up an apparatus[2] noticed a hole about the diameter of a pencil in the sand, and looking down it they spotted something interesting. So they told me about it, and I came over with a little trowel and dug up this:
She’s the biggest wolf spider I’ve ever seen. Her body alone was over half an inch, and her legspan was probably pushing two inches.
Given that she’s a great big wolf spider who was living in a burrow, I’m fairly confident in guessing she’s a Burrowing Wolf Spider, genus Geolycosa. These spiders hang out in burrows that they dig in sandy regions (with a bit of silk lining to keep the tunnel from collapsing on them), and lunge out to grab passing prey.
I don’t think that I can identify her any more closely than that, considering that she’s almost completely obscured by her numerous young. Although, since most of the burrowing wolf spiders are southern species, I suppose we can dismiss all of those and stick with the few species that live this far north (Geolycosa missouriensis, Geolycosa wrighti, and maybe one or two others that haven’t been posted to BugGuide yet).
Her lifestyle is similar to that of the trapdoor spiders, except that the burrowing wolf spiders don’t make a camouflaged trapdoor over their burrow. Oh, and they aren’t particularly closely related. Trapdoor spiders are more related to tarantulas, and the burrowing wolf spiders evolved their burrowing behavior independently.
So, anyway, we let her go in a sandy patch near our house. Hopefully her many children made a home there, and maybe we’ll see their burrows in the spring.
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[1] This area used to be a major copper-mining district. The mineralogy of the copper was pretty unusual. Most copper comes from sulfide ore bodies, which are rich in sulfur, and the copper exists as copper sulfide minerals. They also include the dozens of other metals (many of them toxic) which have a similarly strong tendency to form sulfides. Not here, though. There was evidently very little sulfur up here, and so the copper was deposited as actual pieces of metal ranging from microscopic flecks, all the way up to massive metal boulders. This made it possible to separate the copper from the rest of the rock by simply smashing the ore into sand-size pieces with stamp mills (basically giant hammers). The rock was broken up, but since copper is a ductile metal, it just flattened out and stayed fairly intact. The copper could then be easily separated from the rock just by screening or jigging the metal flakes out of the now-smaller rock particles. This resulted in big expanses of “stamp sand” where the crushed rock was dumped after the copper was removed. As mine tailings go, this stuff is relatively innocuous, as it doesn’t oxidize to make acid mine drainage and release toxic heavy metals the way that sulfide mineral tailings do. But, between the fact that it is sand (and therefore doesn’t hold water), and that there is just enough copper left in it to retard plant growth, we end up with what are basically artificial deserts. Oh, and it is also almost black, so when the sun shines on it, it gets hot enough that any little sprigs of vegetation that manage to start growing get cooked. While it isn’t good for much[3], it is just dandy if you want a broad, open, non-flammable location for model rocketry and similar engineering amusements.
[2] It was one of those projects that you only really want to test out in wide open, unpopulated areas.
[3] Unfortunately, it doesn’t contain much accessible copper anymore. I borrowed a spiral concentrator from my lab and tried using it to recover any remaining copper flakes a couple of years ago, and had not much success. While the ore is maybe around 0.2 – 0.5% copper, it is all so finely disseminated that I’d need to use heap leaching to get it out. Which would work, except that the sand is high in calcite and so will consume too much acid to be economical. I’m currently mulling over some alternative chemistries that might be more effective, maybe I’ll collect a few hundred pounds of it this summer to haul back to the lab and use for a student project.
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I found a large wolf spider with young last year. Since I’m in the south she was probably one of the southern ones. Must have disturbed her while gardening.
Enjoyed your post and learning about the copper.