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O.C. brown widow spider invasion might muscle black widows aside
May 28th, 2009, 8:01 am · 54 Comments · posted by Pat Brennan, science, environment editor
Beneath the patio furniture, under the lips of pots and in the backyard shrubs of Orange County, a strange transformation is taking place.
The brown widow spider — a tropical species unknown in the region just a few years ago — is suddenly everywhere.
Since about 2003, the species has gone from exotically rare to extremely abundant in key urban zones of coastal Southern California, with Orange County as a kind of epicenter, arachnologist Lenny Vincent of Fullerton College reveals in a paper on the spider published this month.
This might mean trouble for its better-known cousin, the black widow, though scientists aren’t sure.
“Anecdotally, people say — and I’ve gotten this from a lot of people — their yards used to have many, many black widows, and now all they have is brown widows,” Vincent said.
A biology professor at Fullerton College, Vincent began his hunt for the spiders after a student brought him a specimen from Brea three years ago.
He told his students to bring him more.
An Orange County Register story in 2006 spread the news that Vincent wanted brown widow spiders sent to him — by mail, if possible, and preferably alive.
“People were just great,” Vincent said. “They brought in specimens from several cities away. They really got into it.”
He estimates that he received about 30 or 40 spiders accurately identified by residents as brown widows, out of the more than 100 specimens collected for his study.
His paper on the spider, published in “The Pan-Pacific Entomologist,” shows the triumphant results: specimens from 18 cities in Orange County, 13 in Los Angeles County, seven in San Diego County and one in Riverside County.
This for a creature that was virtually unknown in California before 2003.
”They seem to be distributed widely,” Vincent said. “You find males, females with egg sacs. I don’t see any reason to think they’re not established.”
No one knows what is causing populations of brown widow to explode here, or how they might displace black widows.
“I don’t know why this would happen — if there’s competition between the two species for locations to build webs, or of one’s outcompeting the other for food,” Vincent said. “I think it would be a great research project.”
Orange County entomologist Nick Nisson suspects climate change could be a critical factor.
“Speaking just of Orange County, there are absolutely just enormous numbers in urban areas of the brown widow spider,” he said. “You’ve got to figure that climate change could have something to do with it.”
Nisson, with the Orange County Agricultural Commissioner’s office, tracks crop pests, not backyard spiders, but says he receives many samples anyway from curious residents. The number of brown widows brought to him has spiked in recent years — from none at all to specimens from all developed parts of the county.
The pattern is similar to that of other non-native insects Nisson tracks as they invade the county, such as the diaprepes root weevil and tropical leaf hoppers.
“These spiders and these insects that were formerly known from tropical areas, or semi-tropical areas, are finding California very hospitable,” Nisson said. “They can tolerate the climate here now. One has to wonder why they couldn’t tolerate it before. I think the answer is temperature and rainfall patterns are very different now than they were in the recent past.” 
Such changes could have triggered a rise in population for an insect that brown widows rely on for food, another possible factor in their sudden population burst, he said.
The spiders, long known in parts of Florida, began an explosive expansion across that state and other parts of the southeast over the past decade.
For Orange County residents, there might be an unexpected benefit. Although brown widows have more powerful venom, the effects of their bites are far milder — soreness and redness as opposed to more serious symptoms, like painful muscle rigidity, that can come from black widow bites.
The hitch apparently is in the delivery. Brown widows appear to release less venom when they bite.
“It appears to be less of a medical concern than the black widow,” Vincent said. “They’re more attractive, and they appear to be less dangerous.”
(Photos of brown and black widow spiders courtesy Lenny Vincent.)
(OC Register brown-widow spider distribution map based on the map in Vincent’s recent paper.)
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“You’ve got to figure that climate change could have something to do with it.”
Yep. If you can’t come up with a valid reason conclude “climate change” before doing any serious research.
My thoughts exactly. Piss poor science.
I noticed these curious spiders a couple months after we switched gardeners. I had a suspicion that the spiders can use gardener equipment as a method of travel throughout the region. Sounds a lot better than the vague “climate change” idea listed in the story.
OMG! I friggin HATE spiders. I’m literally scared to death of them & this is coming from a 35 year old guy…LOL!
Hey, they are undocumented spiders.
I live in Costa Mesa and we have seen an explosion of the brown widows recently. I’ve found many of these in my yard and garage recently. More than of what I would see of black widows.
I used to have a ton of black widows last year. Been trying to keep them under control, but this year, I’ve only been finding the brown widows. Can I have my Biology degree now?
Anybody dare to make a brown/black racial comment???
there are everywhere in my backyard, mating w/ the black widow, creating brown widows
John S is so right. Climate change is a fashionable
trend. Bad scientist, no doughnuts.
Its dry, this happens now and then, get it?
Maybe color? Much harder for a predator to see the brown one on the tan houses, brown dusty landscape, etc.
Come on guys, this is Orange County.
Home of the Trophy Wife Syndrome.
The man said of the browns………. “They’re more attractive,”………so they get more offers to mate.
This has nothing to do with “Climate Change”.
The pictures give me goose bumps. Im all itchy now!!!
I had no problem reading this article. I can’t look at the picture for more than a couple of seconds without getting itchy and breaking out in goose bumps. Creepy little critters. I don’t like the little carnivorous eight-legged insects! Yuck!
LOL I kill anyting with more than 4 legs… especially spiders
Wah wah liberals wah wah crying climate change wah wah wah.
Obama won. Get over it.
Actually the black widow also has formidable competition from another very common spider in the Orange County area known as Steatoda Grossa — or the false widow spider. Both the real and false widow spiders are from the cob weaver family. Despite the fact they are from the same family, they are mortal enemies, however. The false widow spider is known to kill black widows and is thought to be slowly supplanting it.
So between the false widow and the brown widow, the poor black widow spider is facing some competition.
How about the concept that they were recently introduced, piggy backing on something or somehow getting here and now have settled down, much like fire ants?
Before speculating on climate change they ought to figure out how they might have gotten here in the first place. Are they in Mexico and maybe just migrated North or are they from further away and so would have to have been transported in?
Thanks for covering this and making us aware of them. Previously the only 2 poisonous spiders locally that i had been aware of were the black widow and the brown recluse. I may have seen these around and not even realized that they were poisonous.
Also in the photos, the brown widow appears to be larger. Is that just individual specimens or are the brown ones actually larger?
so how do we tell the difference between the brown widow and the brown recluse? i have seen the medical complications from the recluse spider bite.
Well, I forget just what the brown recluse looks like except that it is called the violin spider since it has a sort of violin shaped marking on its abdomen. I forget whether its on the top or underside though. That’s why I was interested in pictures. Well, I’ll take a look at the link. someone gave for pictures.
Check out the link that is posted for pictures. As you go through the pages there is at least one picture of a brown recluse. As i recall, they tend to live up to their name and hide in corners and all and I think they are smaller.
Don’t need to worry about trying to determine if it’s a brown recluse spider – those do NOT exist in California! That’s a myth. We have several species that look like it but we do not have the brown recluse.
article here: http://spiders.ucr.edu/myth.html
I’m seeing a lot more browns than blacks in my yard lately too. Couple of years ago I had a WHITE black widow. It was completely transparent white but had the red/orange hourglass on it’s belly. It was actually pretty cool looking.
about 3 years ago, i found a brown widow spider in my backyard in yorba linda. I haven’t been able to get rid of them. They really like making webs and leaving their spiked egg sacs under my patio furniture and near the base of the bird of paradise plants in my yard. The webs are extremely sticky and the females like to hide behind the densest part of the web in corners of the underside of my patio furniture. glad to hear they are less poisonous than black widows.
blaming their existence here on global warming is just ridiculous though.
Oh, in addition it might be helpful to have photos of any similar appearing spiders and tips on how to distinguish between them. I know I’ve seen some that look something like this, but not sure if it was this or a different, similar appearing one.
I did print out the photos to keep as a reference to aid in identifying any that look like that.
in my research 3 years ago, to try and figure out what kind of spider it was, i found that they originate from Australia.
Haha..I love this Junior College hack, using the Global Warming card, instead of doing more research.
These ideologues are really starting to annoy me.
I love it, racial comments even with the spiders OCR posters never let me down.
We began having brown widows in our house and yard in late 2002 after we moved my Aunt from New Jersey to live with us here in California. We surmised they were in her furniture. The infestation was alarming – we remodeled in 2006 clearing everything out. Now we only see them outside and occasionally in the garage. We have fewer black widows than in the past too.
oc4truth:
If you want to see more pictures of these creepy carnivores, you can do so here: http://images.google.com/images?hl=en&q=brown+widow&btnG=Search+Images&gbv=2&aq=f&oq=
Please don’t ask the Register to post any more pictures of spiders. These two pictures creep me out enough, thank you.
I think that it’s racist that we have white widow spiders.
We have found dozens and dozens of both the brown and black widows in our yard here in Garden Grove. The brown seem more adept at outside living while we find the black more often in the garage and darker spaces. It doesn’t seem like climate change would let one species in while the other species is still thriving (serious climate change would probably kil of the black version) so maybe the browns are just very adaptable.
We owned a chili ranch in Mexico in the 80′s & 90′s and the brown widows were literally everywhere. Never saw them here in the OC, I was born and raised here, but now they are all over my yard and garage.
What is that big black & yellow spider that makes webs about 10 feet across? Has anyone seen that thing? I have spider webs that stretch between trees in my yard. They are large and scary.
the black and yellow spiders that makes the webs that cross your yard, are just garden spiders. they’re harmless
Identifying them and eliminating a few of them early will go a long way towards preventing your entire house and neighborhood from becoming infested. It is recommended to walk around your house in the evening with a flashlight (I know, creepy) and spray anything hanging around. Also use a broom to sweep away webs and egg sacks. Egg sacks should be crushed or burned to completely kill the contents. The egg sacks of the brown widow are easily identifyable as grayish-white “spikey” balls, often about 1/4 inch around. The webs of these spiders tend to be messy, cotton candy looking things – not the nice symetrical hanging webs of harmless orb spiders. They also tend to be located under things, rather than sanning across eaves, etc. Look in low areas, in fences, under furniture and toys, etc. Spray every two weeks in the summer, as they seem to reproduce quickly!
This spider does have the characteristic “hourglass” in red on its abdomen, although it’s sometimes more difficult to see, due to the color of the spider.
Happy hunting!!
I’ve seen them with a white/ light colored “hourglass” as well- I saved several specimens in alcohol and studied them for a few weeks before disposing of them. Spiky egg sacs seem to look just like black version. Also, they seem to have slightly different markings than the one in the photo above- regional differences in varieties?
I thought orb spiders were poisonous, too. Anybody know for sure?
Orb spiders have poison for prey, but unless you are allergic they are no threat to humans (that I know of). Bites would still probably hurt or itch and be red, but not serious. We have some huge ones with red slightly fuzzy bodies that seem to spin gorgeous webs every spring.
Pat — Would I find these brown widows near my tiny beach condo? I’ve never seen a black widow here but do see other spiders. Don’t have big lawns here but do have vegetation. It’s cooler here than inland OC. Just curious. Good story.
I left a pair of shoes outside at night, next day there was a big black widow inside one of them. Got lucky I saw it before I put them on.
Did they come from south of the border for the free medical and food stamps, or to do the work that the other spiders wouldn’t do???/
“An Orange County Register story in 2006 spread the news that Vincent wanted brown widow spiders sent to him — by mail, if possible, and preferably alive.”
Well that just convinced me not to pursue a second career with the Postal Service!
To tossing out the “Global Warming Idealogue” comments –
Nick Nisson, is with the Orange County Agricultural Commissioner’s office. Lenny Vincent is the Fullerton Jr. College Professor.
The article claims that Nisson, not Vincent, is the one with the suspicion that climate change could have aided in the Brown Widows thriving in our area.
As far as Nisson’s suspicion, the article does not directly quote him saying that he suspects climate change.
In fact, the way the remark is written, it leads me to believe that Pat Brennan (the article’s author) failed to note that Nisson believes climate change is only one of the suspected reasons why those spiders are doing so well around here.
I could see the following sequence of events occurring.
Brennan asks Nisson – “Nick, do you think climate change is a critical factor to the expansion of this spider into Southern California”
Nisson replies – “Climate change could be one reason.”
Brennan writes in the article – “Orange County entomologist Nick Nisson suspects climate change could be a critical factor.”
Maybe Pat Brennan should update the article to let us know if Nisson was adamant on climate change being a critical factor or if he suspected that it was just one of many possible reasons.
As far as my idea on how these spiders got here, I suspect they are here because we are near two large ports and some of them hitched rides on the cargo coming into our country.
Maybe some of the spiders will hide out in cargo containers long enough to make their way to China.
Invasive species… The venereal disease of international commerce!
Oh…. one more thing…..
ewwhhhh! EEEwwwwhhhh!! EEEEEWWWWWHHHHHH!!!!!
When I find spiers inside the house, I put them outside alive because they kill flies, and flies carry bacteria everywhere. In the Past I have killed only the black spiders (widows), since they are poisonous.
Do the brown widows decrease the numbers of other spiders or only the black widows?
Also, what is the food of the brown widows?
I loved the article and found it very informative. I believe Dr. Vincent gave us very good information which was very interesting. I also do not kill the spiders around my house and yard. Only the Black Widows. Thanks for printing the article.
My daughter was sitting in the chaise lounge outside two years ago and was bitten by a Brown Widow Spider. I took a picture of it with my Macro Lens to confirm what it was.
We sat in the Emergency Room at Saddleback Hospital in Laguna Hills on a Sunday for 3 hours only for the doctor to tell see us for 1 minute to say, this will affect small children, older people, and those affected with compromised immune systems.
She was just fine.
I am finding Black Widow Spiders everywhere – in patio furniture, in the Trash Can handles, under the eaves, on the lower part of the house, in wrought iron, etc. The key is look for a thick, sticky web and the deep black spider. On it’s belly will be the dark red hour glass shape mark.
They are resistant to pesticides. It takes a while for them to die. I find that Raid Hornet spray works best.
Last night I saw a jumbly looking spider web in my garage, between two empty flower pots. I didn’t see any spiders around, but decided to spray the web anyway. This morning I found FOUR dead spiders in and around the web. At least two of them were brown widows. I had never even heard of this type of spider before reading about them on line a couple days ago.
Thank you OCR for this informative article.
Are the “Orb” spiders the ones tha come out in late August through October and spin the giant webs across 2 trees and hang out in the middle of the web at human eye level?
Hello…yes those are called orb weavers. Interesting color patterns, they scare people, but pretty much harmless.
Jake, the black and yellows are Argiopes, which are a type of Orb Weaver. They can bite but the bite is not a huge threat to humans as they are not poisonous. You can find them on Peter Bryant’s website here:
http://nathistoc.bio.uci.edu/spiders/
and specifically the Argiope is found here:
http://nathistoc.bio.uci.edu/spiders/Argiope%20aurantia.htm
Scary looking spider, I saw one at Arby’s recently with a web from the drivethru window to the speaker. If you can catch one, they make great pets!
First off, ALL spiders are venomous to some degree. Most are considered medically insignificant to humans unless you just so happen to be allergic to the venom of the species you are bitten by. The only three you really need to worry about here in the US that considered medically significant are the following; Black Widow Spider, Brown Recluse Spider, and the Hobo Spider. The only one you need to worry about here in Orange County is the Black Widow spider (Latrodectus hesperus). There are no known populations existing in Southern California of the Brown Recluse spider (Loxoceles reclusa), however there are other Loxoceles species native to Southern California, but all are considered medically insignificant.
As for my theory on why the Brown Widow Spider (Latrodectus geometricus) is becoming far more abundant here in southern california is quite simple.
One, a female will lay anywhere from 1-15+ egg sacs in a single year. I have had captive specimens give me 7 egg sacs from one female! I’ve seen specimens in my backyard with egg sacs in the teens. The first egg sacs layed can have several hundred spiderlings in each and they get less and less with each egg sac laid there after. With black widows I usually only see a couple egg sacs or only one from them.
Two, I believe it has to do with the normal human population automatically killing a black widow if they see it. Whether or not they are beneficial to the enviroment and your backyard. A brown widow doesn’t look like a black widow and is more likely left alone allowing for more adult females to survive and reproduce. Its a numbers game. If you have people killing millions of black widows on sight, but only thousands of brown widows. Then you would see why the brown widow is surpassing in population. As with any species, a population can only handle so much human pressure before it breaks.
That sounds perfectly reasonable to me. I’m glad someone is actually giving a simple answer to why there are so many of these spiders. I live in Tampa, FL – just moved from NYC a few years ago and I never even knew a brown version of the black widow existed.
I killed a brown widow and her mate outside my patio last week and got rid of three egg sacs. I found a fourth egg sac on the other side of the patio and decided to keep it in a jar until the little ones hatched, just to see how many spiderlings emerged. Well, about twenty five came out of that one egg sac. Imagine! My five-year old daughter is captivated with bugs and so we are now observing the spiderlings and feeding them flying ants and other goodies. However, we are NOT going to keep them or release them into the wild because there are already too many of the buggers.
The bottom line is, these spiders produce many offspring and many people are not aware of their existence. Sometimes a simple, non-politically inspired answer is the best one.
I just found one of the brown widow spiders on my back porch patio and captured it in a large jelly jar to show to family in the morning. The red hourglass design is very distinctive and the back of the spider is just as it appears in the photo; light brown with darker spots. I live in Fairhope, Alabama, just outside of Mobile. I have never seen one of these spiders in this area. Does anyone know if they are indigenous to southern Alabama? I think I’ll leave it outside even though it’s in a sealed jar. Just kinda gives me the creeps looking at it.
I now have a case of the heebee jeebees..
I found a few of these in our yard in Orange last summer… They were so odd looking cuz they were brown but had orangish-yellow hour glasses on their bellies… so my husband googled for info and found that they were both Brown Widow Spiders… we regularly spray and are always keeping a lookout for more of them, and kill them immediately if we see one… they like our BBQ for some reason!!!
You can get better pictures and more info if you google them…