Latrodectus Invasive

[The Snark]

So far not found in this immediate area.
Suburban area 9 miles outside Chiang Mai in a restaurant under a chair. Telltale strong webbing, egg sacs appears to be Geometricus. 7 sacs, all hatched. A male appears to be a few inches away.

MALE?

And mommy

Images have been sent to Senckenberg for verification

 

[NYAN]

It’s not a male. It’s a young female probably. It’s definitly geo though, which doesn’t a surpisise me since they are everywhere.

 

[The Snark]

It’s not a male.

The possible male was that one picture of a small non-descript therididae. Obviously the main event in those pics is a female, in full assembly line mode, and we can now safely assume another piece of paradise lost to globalism. IE, established invasive dangerous spider. People here are inured to spiders as being harmless and ignore bites. That cost a man's life down in Denchai a few years ago, ignoring the bite of a recluse. With Geos in high density populated areas, going by their propensities, proclivity and reproductive ability a full scale invasion is more or less fait accompli.

This, my first encounter with these in this country, was a little weird. I spotted a something under one of the chairs in my favorite restaurant. Turning the chair over, a painfully obvious Geo egg sac. Closer inspection revealed 6 more and the spider. I took the chair home to do the capture. In disassembling the web I used a piece of strong high tensile wire. A reminder of these sporks. The web so strong it was bending the wire out of shape. 7 sacs, all with an opened exit hole.

 

[chanda]

...established invasive dangerous spider. People here are inured to spiders as being harmless and ignore bites. That cost a man's life down in Denchai a few years ago, ignoring the bite of a recluse. With Geos in high density populated areas, going by their propensities, proclivity and reproductive ability a full scale invasion is more or less fait accompli.

I'm not sure I'd consider them particularly dangerous. Yes, they do have that Latrodectus venom - but their bite is supposed to be a lot less severe than that of the black widows because they inject less of the venom per bite. Also, they are generally quite timid and reclusive and reluctant to bite.

They have already invaded Southern California, displacing the local black widows (L. hesperus) in many areas. There are oodles of geometricus at my son's elementary school - under the outdoor lunch tables, in the fences and the handrails on the stairs, under chairs, benches, hose reels - pretty much anywhere they can find a dark(ish) nook or cranny to nest - yet despite living in close proximity to a bunch of children, we've never had anybody bitten or had any problems with them. If anything, I feel a bit safer with them there because they have displaced the hesperus that used to be all over campus just a few years ago. It's rare to find a hesperus at the school anymore! (They are, however, thriving out in the canyons - and in my yard/garage/shed which have not yet been invaded by the geometricus.)

 

[The Snark]

Jaeger just gave me a tentative probable Geo. Sigh.
The problem with Geos here is people completely ignore spider bites. Until the globalism invasion the worst you can expect is a bit of a sting on out to a wham from the big black scorps that can make you feel like death warmed over for 24 hours or the minax bang that hurts like a red hot nail stab for a few hours. All untreatable and just wait it out. Nothing highly dangerous, until now.

 

[Ungoliant]

Suburban area 9 miles outside Chiang Mai in a restaurant under a chair. Telltale strong webbing, egg sacs appears to be Geometricus.

Those are definitely L. geometricus sacs. It wouldn't surprise me if they ended up in Asia, inadvertently spread by commerce. They are hardy and tolerate a wide range of conditions.

People here are inured to spiders as being harmless and ignore bites. That cost a man's life down in Denchai a few years ago, ignoring the bite of a recluse.

FWIW, brown widows may not actually be dangerous (unlike their black widow cousins). Rick Vetter on the advent of brown widows in California:

In February of 2003, specimens of the non-native brown widow spider, Latrodectus geometricus, were discovered as part of the Los Angeles Spider Survey being conducted by the Los Angeles County Museum of Natural History. This was an interesting discovery and one that is mostly of scientific interest to southern California arachnologists.

However, the ensuing media attention that was given to the spider has created the false impression that the brown widow is a new danger in southern California. Reports have correctly stated that the spider's venom is fairly potent but because the spider injects so little, it is not of major consequence. Yet one hyperbolic report stated that the spider hasn't killed anyone so far. This is not surprising because the brown widow is not a dangerous nor deadly spider. Even though it has venom of high toxicity, this is typically determined with injections of venom into mice or rabbits and conclusions from this are inferred with little real-world relevance.

Much more relevant is the effects of actual spider bites. A South African medical journal reports on the bites of 15 brown widows in humans (Muller 1993) . Only two symptoms of brown widow envenomation were reported in the majority of bite victims: 1) pain while being bitten and 2) a mark where the bite occurred. That's it. Not much more. The bite of the brown widow is about the same as any non-poisonous spider. It hurts and leaves a little mark on the skin. It is no big deal. There are none of the serious, protracted symptoms that one would exhibit when bitten by a black widow.

So even though the non-native brown widow is virtually harmless, it is getting all this publicity and people are concerned about it. The hyperbolic response of the media and the general public to this new resident of southern California is ludicrous considering there are millions (maybe billions) of native black widows, Latrodectus hesperus, all over southern California, which have a far more poisonous venom than the brown widow, poses a much greater potential danger due to its great numbers and venom toxicity than the brown widow could ever hope to pose, black widow bites do occasionally happen, no one dies, people see black widows all the time, kill them and are not particularly concerned about them.

Yet you don't see media articles about the black widow because it isn't "news". The brown widow is not a spider of medical concern and is not likely to become one. It isn't dangerous where it currently lives and there is no reason to believe that all of a sudden it will become dangerous now that it is in southern California. The native black widow is still the major spider of potential medical importance in southern California, always has been and always will be here.

Vetter also wrote an illustrated guide on distinguishing between brown widows and black widows.

 

[The Snark]

@Ungoliant Quite helpful. As mentioned, the major concern is people's lackadaisical attitude towards spiders. As the man down in Denchai that was bit by a recluse and ignored it. Even when he developed septicemia he didn't go to the hospital until he had an extremely high fever, irregular heartbeat and respiratory distress. Sort of the opposite of the first world's freak out over any spider, people just shrug. Cleaning out webbing is always done casually by hand. Kids even play in spider webs and consider the larger huntsman and Ts toys.
This casual take on spiders has even affected me. I clean out webs with my hand without giving it a second thought now and I come from L Hesperus central.

But on the flip side of the coin, show the average rural Thai a caterpillar and it's major freak out time just like arachnophobia in the US. But with a very good reason. Everyone has heard the stories of the slightest touch can cause excruciating pain and even death.

Yer anecdote. I had a friend from the US here. He followed me in his car to a friends garage. Just as he was parking he let out a half bellow half scream and came out of the car waving his arms wildly and dancing around all over the place. All my friends at the garage were wide eyed WTF??? I looked it the car and there was a really hefty sized Venatoria on the seat. I pointed it out to my garage friend. He reached in, grabbed the spider and held it up for all to see. A couple of helper mechanics were real close to ROTFL their arses off. Everyone lost it. The usual Thai politeness and reserve was dropped. My mechanic's wife had her head down on her desk, laughing so had she had tears running.
Here was this huge burly man completely freaked out over what was considered a silly child's toy.

 

[NYAN]

Geometrucus are harmless. I let one bite me and it was like a bee sting.

The web in the photo is abandoned. The spider you found isimmature also by the looks of it. There are probably many more nearby though.

 

[The Snark]

I kept her in a container where she settled down and cranked out one more egg sack. She hasn't turned out any more or eaten for nearly 3 weeks. This morning I turned her loose in the garden and destroyed her eggs. Let her live out the rest of her life in our little preserve and maybe snag a few mosquitoes along the way.

 

[TheSpiderChick]

@TheSnark, I am really perplexed as to why you released the spider in your garden?
You were bemoaning globalism and invasives, understandably. But then you transported an invasive species from where she was found and released her at a new location, where she could easily lay more egg sacs and populate that new area with her offspring.
I understand that you destroyed the egg sacs she had already laid. But Latrodectus can lay over a dozen egg sacs, and a three week gap is not an indication that she wouldn't lay more later.

Please know that I am not attacking you, The Snark. I am just confused by your actions, and I want to educate others.

As someone who has studied spiders for 20+ years, with a husband that has worked with invasive species for that long, I would advise against anyone EVER releasing an invasive species in ANY location where it was not collected.
Please never release a non-native species anywhere.

 

[The Snark]

@TheSnark, I am really perplexed as to why you released the spider in your garden?

I'll be the first to admit my logic is highly flawed. Yes, she may very well have got a couple of good meals, found a safe place to make a web and hide and may be churning out egg sacks right now. My twisted weird logic:
1. There really is no dark nooks and crannies in the yard that Latro prefer. The opportunities for them to infest the areas like what is happening in Hesperus native haunts.
2. For every predator of Latro in the California area we have several thousand. If she can manage to survive running the gauntlet of a recovering rain forest habitat, have at it. I have a reasonably good chance of keeping track of a therididae web in that area.
3. Pholcid country. Even if she finds a suitable location and establishes herself, every possible location around here is occupied by dozens of pholcids. An additional gauntlet to run.
4. She is/was a Geo after all, and I was right. Returning to that restaurant where I found her I found 3 more occupied webs, 2 with egg sacks. It's inevitable. S.E. Asia is now home to them.
5. Sigh. I've put down way way way too many animals in my time with all sorts of rationalized justifications. I'm now drawing lines in the sand, even if they are dementedly illogical ones.

What was impressive and a little disturbing to me was the females in those new webs were TINY! They looked immature but undoubtedly were responsible for the egg sacks.
I'm getting the unscientific impression Geo is still in flux, capable of one or two generation mutation depending on habitat. That would certainly help explain why they are forcing out the other Latro species.
It appears Geo's can produce viable sacs pre penultimate under certain circumstances, forced evolution if you will, which sounds positively weird. Or possibly they are undergoing fewer molts before maturity??

 

[TheSpiderChick]

OK @The Snark, I can see how you came to the decision, flawed as your logic may be. I still don't agree with your reasoning, but I understand.
I also really get the not wanting to euthanize her. This is something I ALWAYS struggle with. I currently have a problem with invasive Steatoda nobilis in my back yard (In Northern California), and they are clearly displacing other spiders, but I am not doing what I should to control them because I just hate killing things so much. (plus they are so pretty!) It's a real struggle. You could have just released her back where you originally found her. That way, even though you are not fixing the problem, you are at least not contributing to the spread of an invasive species because they were already there. Just something to think about. Carry on...

 

[TheSpiderChick]

What was impressive and a little disturbing to me was the females in those new webs were TINY! They looked immature but undoubtedly were responsible for the egg sacks.

I suspect these were simply immature spiders that were still hanging around where the egg sacs were. That is not uncommon with cobweb weavers. The mother spider may be gone, but these partially grown juvies just took up residence in the same area where they hatched. I don't think you can assume that the spiders you saw were responsible for the egg sacs. I've even seen Pholcids chilling out right next to a Steatoda nobilis egg sac, and now that I think about it, a Steatoda nobilis who made her retreat connected to a Zygiella x-notata egg sac. So proximity doesn't prove ownership.

It appears Geo's can produce viable sacs pre penultimate under certain circumstances, forced evolution if you will, which sounds positively weird. Or possibly they are undergoing fewer molts before maturity??

Is this a conclusion you've come to just from your observation in this situation? Or is it something you've read in a Scientific Journal?

 

[The Snark]

I suspect these were simply immature spiders that were still hanging around where the egg sacs were.

I removed all the egg sacks and did a pretty careful search for other mature spiders in the area. The new sacs were under plastic chairs in a public seating area so it was unlikely mature ones had moved in, laid sacs, then left.

Is this a conclusion you've come to just from your observation in this situation? Or is it something you've read in a Scientific Journal?

Purely observation. I spend an inordinate amount of each day simply studying animals and their interaction with the immediate environment. Over time I get an general innate feel of how an ecosystem is functioning but mostly I notice and pay close attention to anomaly's and outside-the-envelope variations. With Latrodectus the conclusion I've reached is the common ones, Hesperus, Mactans and Variolus are all ancient opportunist, long time established in comfort zone niches in the ecosystems. Geo has, for reasons unknown, altered into an invasive, taking advantage of globalism, a newcomer ignoring boundaries. Much more prolific than the others and easily able to establish itself within their territories. I compare to the Himalayan blackberry introduced into the Pacific northwest.


The overall impression I am getting is Geo has moved into a niche. For the most part, S.E. Asia has almost no therididae if you discount the pholcids. It is an ultra target rich environment, tropical with jungle, rainforest, recovering forest, fallow farmland, abandoned housing projects, rural communities and urban environments often within a few square mile area. Geo couldn't have picked a better niche. Time and opportunity for it to strut and maybe expand it's genetic capabilities.
I think that, probably, the greatest threat to the Geo here is the pholcids. While Latro goes to ground and parks once mature, the wandering slings will become a natural diet for the pholcids.

 

[The Snark]

OK @The Snark, I can see how you came to the decision, flawed as your logic may be. I still don't agree with your reasoning, but I understand.

Regarding life and death, I combine the reason and rationale of a traditional native - Sioux, with Zen Buddhism. And yes, they mesh very well. But both are lines of thinking that cannot be explained except to other adherents of those schools... and then no explanation need be voiced. Could be voiced, any more than one could hold a tactile koan in one's hand.
But consider that animal not as an invasive, not as a potential harm or threat, not even as an animal. Perhaps that spider had the spirit of a warrior, facing it's own trials. What then action if any should one take in regards to it's life, or it's relationship with it's spirit?

That way, even though you are not fixing the problem, you are at least not contributing to the spread of an invasive species because they were already there. Just something to think about. Carry on...

I decline the nomination of almighty all seeing all knowing bringer of justice and absolute rightness. The problem isn't a problem. There is no absolute right and wrong. Life is in continual flux. The best we can hope to do is tread as lightly as possible, establish a code of ethics and stand by it unwaveringly to the end.

The seeker: "Talking to you is like talking to a wall."
The sage: "Buddha once sat before a wall and when he arose he had gained enlightenment."
The seeker: "Do you compare yourself to Buddha?"
The sage: "No. Only to the wall."

 

[Argos]

It’s a shame that native Latrodectus displacement has become an issue as L.geometricus is such a beautiful spider with so many color morphs, black being my favorite (photo attached). In my experiments with breeding them in captivity vs. US native species.. L.geometricus is by far the most fit. Nothing comes close. And, our absolute least fit native Latrodectus in the US is the one in my avatar - L.bishopi which I’ve raised a few hundred of for release over the years. For the most part, Latrodectus are not a problem as long as people remember to have a look in hand holds etc for the spiders, under any outdoor furniture, equipment, etc. Nothing unreasonable and not an outwardly aggressive spider.