Latrodectus woes

[darkness975]

Does anyone know of any resources that discuss the phenomenon of the Latrodectus geometricus invasion and what effect they are having on our native Latrodectus spp. ?

 

[chanda]

I don't know of any resources, but I can verify anecdotally that they are displacing the native black widows, Latrodectus hesperus, here in Southern California. I saw that happen both in my own yard (at my previous house) and also at my kids' school.

We used to have a healthy black widow population at the school, but I haven't seen one in the past few years (since the geometricus moved in). On the other hand, the geometricus can now be found in pretty much every hand rail and fence on campus.

At my previous house, we used to have a bunch of black widows living in the garage and the garden shed, and would find their corpses when cleaning up the mud dauber nests on the fire sprinklers in the garage. (I'm fine with mud daubers normally - but having them on the fire sprinklers just doesn't seem safe.) Once the brown widows moved in, the black widows started disappearing - and the spiders in the mud daubers' nests switched over to primarily geometricus.

I have not seen the brown widows at my current house - yet - and still have a healthy L. hesperus population in my garage, hose reels, and around the foundations, but I'm sure it's just a matter of time.

 

[NYAN]

The only places I find Hesperus are away from civilization. All I ever find in urban environments are geometricus pretty much.

 

[darkness975]

I don't know of any resources, but I can verify anecdotally that they are displacing the native black widows, Latrodectus hesperus, here in Southern California. I saw that happen both in my own yard (at my previous house) and also at my kids' school.

We used to have a healthy black widow population at the school, but I haven't seen one in the past few years (since the geometricus moved in). On the other hand, the geometricus can now be found in pretty much every hand rail and fence on campus.

At my previous house, we used to have a bunch of black widows living in the garage and the garden shed, and would find their corpses when cleaning up the mud dauber nests on the fire sprinklers in the garage. (I'm fine with mud daubers normally - but having them on the fire sprinklers just doesn't seem safe.) Once the brown widows moved in, the black widows started disappearing - and the spiders in the mud daubers' nests switched over to primarily geometricus.

I have not seen the brown widows at my current house - yet - and still have a healthy L. hesperus population in my garage, hose reels, and around the foundations, but I'm sure it's just a matter of time.

The only places I find Hesperus are away from civilization. All I ever find in urban environments are geometricus pretty much.

This is sad. The typical idiot believes that it is a Godsend because supposedly they are less venomous, which is not confirmed, but they are obviously disproportionately dispersed. The whole ecosystem is threatened with the seemingly imminent demise of an entire species of Spider. Unless people can confirm that not every state or habitat is at risk of being overrun.

Certain wasps and such that are trained to go after Widows are not helping since they do not seem to be cued in to go after the brown widows.

 

[NYAN]

This is sad. The typical idiot believes that it is a Godsend because supposedly they are less venomous, which is not confirmed, but they are obviously disproportionately dispersed. The whole ecosystem is threatened with the seemingly imminent demise of an entire species of Spider. Unless people can confirm that not every state or habitat is at risk of being overrun.

Yup it’s stupid. I hear people say that it’s a good thing also. As for them being less venomous, it is true. Their venom is more potent drop for drop than any other Widow, but they inject far less making them non medically significant.

 

[myrmecophile]

My experience has been the same as others, once the geometricus move hesperus are gone. Some time back I had someone here ask If I would sell him geometricus when I told him no, "when I find them I kill them" His response was as follows.

" The spider is a beneficial organism to farmers. What you are doing is counter productive. You'd be better served doing this to ants. I have several organic methods of killing them from use of parasites to specialized viruses. I hope to find even more effective vectors in the new year. The brown widow's success as a beneficial predator is a bar that has been set. We must responsibly eliminate pest insects like ants that damage food crops. Here's to a productive New Year."

Silly people

 

[NYAN]

My experience has been the same as others, once the geometricus move hesperus are gone. Some time back I had someone here ask If I would sell him geometricus when I told him no, "when I find them I kill them" His response was as follows.

" The spider is a beneficial organism to farmers. What you are doing is counter productive. You'd be better served doing this to ants. I have several organic methods of killing them from use of parasites to specialized viruses. I hope to find even more effective vectors in the new year. The brown widow's success as a beneficial predator is a bar that has been set. We must responsibly eliminate pest insects like ants that damage food crops. Here's to a productive New Year."

Silly people

I remember that response. However, I think that’s selling them to people who will keep them as pets is no issue. When I see them, I capture them so they can’t reproduce outside and damage the native species.

 

[Quetzalcoatl Nyarlathotep]

I kill all cob-web spiders in my widow shack. My northern widows are doing well, considering that I only decided to keep 13 and let the 300 or so balloon away from the shack. I was hoping that they'd stay in there, but spiders do what they want with reckless abandon. Those pholcids though, they did a number on my babies. Which is why I have a burning fury for them now. It would seem contradictory I know, but I cannot stand them, or most any cosmopolitan species, humans included. The popular are so because of a corrupt way of thinking. The extraordinary are often the ones seldom seen.

 

[darkness975]

I'm not a fan of cellar-dwellers either, but at least they are native to the country. The brown widows on the other hand well they're basically signing the death warrant for the Black Widow.

 

[lostbrane]

For a couple of years at work I would see L. hesperus sacs on the underside of vehicles (typically ones left out and about in some lot). Now it's only L. geometricus sacs.

 

[checkmate]

I'd also like to read any resources regarding this subject. Just moved into a house in Orange County and nothing but geometricus in the backyard (found 12 so far with a flashlight). No hesperus.

 

[RTTB]

We have both in Yucaipa,CA and both species in my backyard. I can confirm I see less and less hesperus each year. When I do see them I have been seeing them in more fringe areas and the geometricus have taken over the garage shed and house eaves normal hesperus spots. This is the real deal. I have yet to see a geometricus in my Colorado and Mojave Desert spots when out collecting scorpions and such though.

 

[The Snark]

The whole ecosystem is threatened with the seemingly imminent demise of an entire species of Spider.

The ecosystem does seem to be altering. But this alteration needs to be observed. Geos have found an niche in the ecosystem, but Hesperus range is far wider than Geos will tolerate - the hot arid areas. Hesperus had no competition and every damp hole had one. Now Hesperus is receding and we need to observe how nature establishes a new balance.

 

[USMuscle9403]

Geometricus is completely taking over here in South Carolina. I scarcely see mactans or variolus anymore.

 

[darkness975]

Geometricus is completely taking over here in South Carolina. I scarcely see mactans or variolus anymore.

@The Snark ?

 

[The Snark]

I think that's two ?. Or more. Geos are environmental opportunists. One of the first questions needing answered is, is this natural or were they aided? Nature is very intolerant of holes, vacancies in ecosystems. She will fill them with something. And always living organisms aren't isolated but part of a chain. No doubt catastrophic declines or extinctions have happened countless times over the eons. Probably a few million times in the past century alone, sometimes with far reaching unforeseen ripple effects.
Geos have been noticed most often in close proximity to human habitation. It's quite likely, humans are responsible for their spread, directly and or indirectly. Eventually their population will reach a tipping point and experience a decline, or they will become the new paradigm. Eternal cycles of evolution, sporting, experimenting, adapting, replacing or dying out.
It's really just another lesson for humans. We have no idea what effects we are having on the global ecosystems. The gentler and more cautious we walk on mother earth, the better. As for the ecosystems, the environment, they should be viewed as a textbook being constantly revised as we read. Let's read the rise of L Geometricus for the next few years.

 

[Stan Schultz]

Does anyone know of any resources that discuss the phenomenon of the Latrodectus geometricus invasion and what effect they are having on our native Latrodectus spp. ?

No direct references, but several further places to look:

1) I did a search (using Yahoo!) with the search string hesperus geometricus invasive and got well over 500 hits. Also substitute mactans for hesperus. Or simply use geometricus invasive. Also use Google. I'll let you to go through all these to see if there's anything useful. (Yes, I know you've probably already done this. But remember that a lot of other people are also going to read your query and my response, and this paragraph is intended more for them.)

2) You might contact an arachnologist by the name of Rick Vetter <rick.vetter@UCR.EDU> with your question. He seems to have taken an interest in both the genera Latrodectus and Loxosceles (widows and recluses respectively).

3) Contact an animal behaviorist, Dr. Maydianne Andraden (University of Toronto, Scarborough at <mandrade@utsc.utoronto.ca>) and/or her grad student, Charmaine Condy <charmaine.condy@mail.utoronto.ca>. Charmaine is currently putting the finishing touches on her PhD thesis on the taxonomy of the genus Latrodectus.

As far as I know, none of the people who are mentioned above are actually working on the issue of the invasive nature of L. geometricus, but they all have their fingers on the pulse of the genus, so to speak, and are more likely to know where to find the information you seek.

Best of luck...

 

[darkness975]

No direct references, but several further places to look:

1) I did a search (using Yahoo!) with the search string hesperus geometricus invasive and got well over 500 hits. Also substitute mactans for hesperus. Or simply use geometricus invasive. Also use Google. I'll let you to go through all these to see if there's anything useful. (Yes, I know you've probably already done this. But remember that a lot of other people are also going to read your query and my response, and this paragraph is intended more for them.)

2) You might contact an arachnologist by the name of Rick Vetter <rick.vetter@UCR.EDU> with your question. He seems to have taken an interest in both the genera Latrodectus and Loxosceles (widows and recluses respectively).

3) Contact an animal behaviorist, Dr. Maydianne Andraden (University of Toronto, Scarborough at <mandrade@utsc.utoronto.ca>) and/or her grad student, Charmaine Condy <charmaine.condy@mail.utoronto.ca>. Charmaine is currently putting the finishing touches on her PhD thesis on the taxonomy of the genus Latrodectus.

As far as I know, none of the people who are mentioned above are actually working on the issue of the invasive nature of L. geometricus, but they all have their fingers on the pulse of the genus, so to speak, and are more likely to know where to find the information you seek.

Best of luck...

Nice to see you again, Stan!

Thank you for the contacts. I will formulate a message and give it a try.

 

[The Snark]

I will formulate a message and give it a try.

A properly formatted email to Vetter is a very good idea. He's usually very responsive to obviously informed academic inquiries. Crawford is similar but the Geo is not really in his geographic scope of expertise.

 

[darkness975]

A properly formatted email to Vetter is a very good idea. He's usually very responsive to obviously informed academic inquiries. Crawford is similar but the Geo is not really in his geographic scope of expertise.

Appreciate the info.

Is L. Geo proven to not tolerate cooler or wetter climates ? If so that might hopefully mean L. hesperus will survive. At least somewhere.