Another What Kind Of Spider Is This?

Juan1

Arachnopeon
Joined
May 5, 2017
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1
I found this guy in my back yard the same day I killed what appeared to be a black widow. I live in inland San Diego where it is more desert than coastal. Can you help me identify it?
 

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The Snark

Dumpster Fire of the Gods
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Aug 8, 2005
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Sure does look like the Geo is going to replace L Hesperus. Inland San Diego area is pretty much ground zero for Hesperus. Now Geo's are popping up like mushrooms in a cow pasture after a rain. It is pretty amazing how short a period of time is involved. A species that, ostensibly, has been established for quite a few thousand years displaced in a few decades.
 

Rick McJimsey

Arachnoprince
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I've kept a lot of geometricus and hesperus, and the geos consistently make many more eggsacks, sometimes 3-4x as many, in the same amount of time as hesps. It's rather terrifying
 

The Snark

Dumpster Fire of the Gods
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This Geo epidemic is very strange in one way. The phenomenon of an organism finding a niche in an ecosystem is well documented and understood. But the Geo appears to have made it's own niche out of thin air. No precedent, no common denominator. How did this happen? Why now and not 100 or 1000 years ago?
 

myrmecophile

Arachnolord
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Dec 22, 2006
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Those bloody things are common as dirt in San Diego, I have noticed they will set up house keeping in places no self respecting L. hesperus will use.
 

Ungoliant

Malleus Aranearum
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I have noticed they will set up house keeping in places no self respecting L. hesperus will use.
They seem to tolerate a wider range of living spaces than our native L. mactans as well. Sadly, all I ever see these days are L. geometricus, never L. mactans.
 

USMuscle9403

Arachnosquire
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Nov 30, 2004
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It's happening everywhere, it seems. Just a few short years ago, there were no geometricus anywhere here. Now, there are no mactans or variolus but the Browns are everywhere. This all happened very quickly.
 

Biollantefan54

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Jul 3, 2012
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I'm not sure what happened here in NC, a couple years ago, all I found was geometricus. They were everywhere, now, I can't find any here. I know where a couple L. mactans are though but I haven't found a geometricus in over 2 years
 

Python

Arachnolord
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Mar 21, 2005
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This Geo epidemic is very strange in one way. The phenomenon of an organism finding a niche in an ecosystem is well documented and understood. But the Geo appears to have made it's own niche out of thin air. No precedent, no common denominator. How did this happen? Why now and not 100 or 1000 years ago?
You are right, of course, but humans have pretty much done the same thing and I think we have been quite a bit more destructive. There isn't a single habitat on our little blue marble that we haven't at least visited. From the highest peaks to the deepest ocean trench, we have left our mark everywhere on our planet and a few others. Of course I find Latrodectus far less dangerous and much more personable (present company excluded that is). I would much rather have a house full of geos than inlaws lol.
 

myrmecophile

Arachnolord
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Dec 22, 2006
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625
I'm not sure what happened here in NC, a couple years ago, all I found was geometricus. They were everywhere, now, I can't find any here. I know where a couple L. mactans are though but I haven't found a geometricus in over 2 years
A lot of times with these invasive species the population will quickly climb then peak before crashing to a more reasonable level. We can only hope that will be the case with this miserable species.
 

Biollantefan54

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I found them under tables, under porch overhangs, under he grooves of the trashcan, in piles of siding, then boom, all gone. I can find traces of their old eggsacks in some areas but can't find them anywhere. Just the normal spiders now. Really cool!
 

The Snark

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A lot of times with these invasive species the population will quickly climb then peak before crashing to a more reasonable level. We can only hope that will be the case with this miserable species.
Time will tell. Hesperus certainly has had a heyday fitting into the artificial habitats humans have created. Now Geos are displacing them and moving into those niches. With natural predator populations drastically reduced or even entirely eliminated it is anybodies guess what is going to happen. Perhaps a die off and recession or like the Himalayan Blackberry in the Pacific northwest, no end in sight.
 

TheSpiderChick

Arachnopeon
Joined
Oct 14, 2010
Messages
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I'm not sure what happened here in NC, a couple years ago, all I found was geometricus. They were everywhere, now, I can't find any here. I know where a couple L. mactans are though but I haven't found a geometricus in over 2 years
That's really interesting! I wonder if it is related to recent climate patterns or something. For example, 4 years of epic drought in California made some pretty big changes in our local flora and fauna, at least temporarily. I don't know. I'll have to ask some of my colleagues (arachnologists) with expertise in those areas if they have any insight.
 

TheSpiderChick

Arachnopeon
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Oct 14, 2010
Messages
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Time will tell. Hesperus certainly has had a heyday fitting into the artificial habitats humans have created. Now Geos are displacing them and moving into those niches. With natural predator populations drastically reduced or even entirely eliminated it is anybodies guess what is going to happen. Perhaps a die off and recession or like the Himalayan Blackberry in the Pacific northwest, no end in sight.
According to a colleague who has extensively studied the brown widow's spread in California, they're found only in areas of human habitation, not in natural habitats, while the L. hesperus populations are still healthy in the natural areas. Pretty fascinating.
 
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