#latrodectus geometricus

[rushofficial]

latrodectus geometricus . the brown widow

brown windows currently are infesting my work and i could not be more pleased. love my aggressive little girls 🤭

[crudlynaturephotos]

[jumping-widow]

Few spiders in the United States have a more fearsome reputation than black widows. But throughout the South, the bulbous arachnids with red hourglasses on their bellies are engaged in a lethal competition with the brown widow, a relative from abroad — and they’re losing.

This isn’t a case of one species outcompeting another for food or habitat. In research published Monday in the Annals of the Entomological Society of America, biologists found that young brown widow spiders have a dramatic tendency to seek out and kill their American cousins.

“Brown widows will aggressively go after black widows, chase them down,” said Louis Coticchio, a science tutor at St. Petersburg College in Florida and an author of the paper. “They don’t play well with being neighbors.”

Three species of black widows are native to North America, including the Southern black widow, Latrodectus mactans. Exceedingly shy insect hunters, black widows like to live in crawl spaces, woodpiles and sheds. This fondness for human habitation does occasionally lead to people getting bit — 1,004 cases in 2021, according to America’s Poison Centers ��� but deaths are extremely rare. “Black widows generally don’t bite when harassed,” preferring to run, play dead or flick webbing at a poking finger, Mr. Coticchio said. “It’s only pinching them that’ll get you bit.”

Mr. Cottichio spent several years working as a venomous species zookeeper in California, looking for spiders in his spare time. While hunting for western black widows in suburban Los Angeles, he noticed that wherever they and brown widows overlapped, the black widows eventually disappeared. Upon starting his bachelor’s degree at the University of South Florida, he found the same thing. “Every time I returned to a site, there were less and less of them until there were none.”

Brown widows — a closely related species — arrived in Florida around 1935, probably from South Africa. A single mother produces multiple egg sacs and potentially thousands of spiderlings. Like black widows, brown widows like to live around people. Brown widows are less venomous than their native cousins, and aren’t at all shy.

To figure out why, Mr. Coticchio and his colleagues looked at the mathematical population modeling of the two widow species, which showed that both black and brown widows were more likely to get eaten than to starve — suggesting that they aren’t competing over scarce prey.

When they paired brown and black widows in container habitats — along with other related species like red house spiders and triangulate cobweb spiders — the researchers found that brown widows were 6.6 times as likely to kill black widows than other species. Young brown widows in particular made a beeline for their native cousins, eating them 80 percent of the time.

Adult brown widows were less belligerent, the researchers found, and significantly less likely to successfully kill a black widow hiding in an established web. But they still instigated observed attacks. “Southern black widows were never the aggressor and always the prey,” Mr. Cottichio said.

What drives such predation attempts? One possibility lies in the spiders’ respective temperaments, the researchers suggest: Brown widows tend to be bold, investigating nearby webs and attacking spiders that don’t resist. House and cobweb spiders challenge them, and brown widows often go on to coexist with them peacefully. The shy, retiring black widows generally tried to escape, fighting back only as a last resort.

“We have found similarly high levels of aggression and activity in invasive brown widows in Israel,” said Monica Mowery, a spider biologist at Ben-Gurion University of the Negev who was not involved in the new study. “One key remaining question is whether brown widows are outcompeting local species” in other parts of the world that they have invaded, she said.

In the Southern and Western United States, the outlook for urban-living black widows isn’t good. But the species does have a fallback: Black widows like deserts and woodlands as much as suburbs, Mr. Cottichio said, while brown widows prefer urban and suburban areas. The ongoing contest might end with black widows being cast out of crawl spaces and attics in favor of the wilderness, where their aggressive cousins won’t follow.

In the meantime, Mr. Cottichio said, if you find yourself on a property with black widows, don’t be so quick to kill them: They’re already having a bad time.

“If you have some on your property,” he said, “do a good deed, and move it outside somewhere.”

A version of this article appears in print on March 21, 2023, Section D, Page 2 of the New York edition with the headline: For Black Widows, a Brown Cousin Is the Real Killer.

[2t2r]

Les araignées mangent les serpents (aussi)

Nouvel article publié sur https://www.2tout2rien.fr/les-araignees-mangent-les-serpents-aussi/

Les araignées mangent les serpents (aussi)

[jumping-widow]

Very beautiful 😍 pretty sure that's a Brown Widow, however, as Brown Widow egg sacks can have that spikey appearance whereas Black Widows have more spherical egg sacks. The name Brown Widow is sort of a misnomer because while they are oftentimes brown they can be a dark black as well.

Beautiful lady with egg sacs. :3

[rurouniart]

Latrodectus geometricus (2023) Los Angeles, CA Scaled up x6.66 onto 23 cm x 30 cm sheet Bathed in acetic acid prior to freezing Abdomen markings lost post-freeze, followed by rapid decay and leaking biological fluids

[mossiestpiglet]

Caught some widow spiders that were on my neighbors porch and scaring them, one is a big mama western black widow and so I’ll be releasing her in the nature trail by my house. The other is a brown widow and they’re invasive here so im keeping her as a new pet and gave her some sticks from the yard and leaf litter to make a web on.

[khaosb]

Brown widow

[beastspiders]

Latrodectus geometricus by Beast Spiders on YouTube #latrodectusgeometricus #latrodectus #geometricus #widow #black #blackwidow #spider #spiders #spider #BeastSpiders (w: Kraków) https://www.instagram.com/p/Cn2p0fgscPw/?igshid=NGJjMDIxMWI=

[onenicebugperday]

Hey! Love your blog and all the great bugs! I saw you label something as a false black widow a few days ago- I didn't know that was a thing?? If you have the time, how can you tell them apart? Is one safe and the other not?

Oh yes! It’s a thing. Widow spiders (black widows, brown widows, and a few others) are in the genus Latrodectus. False widows (false black widows, triangulate combfoots, noble false widows, rabbit hutch spiders, etc) are in Steatoda, but they’re both in the family Theridiidae, so they look very similar and are closely related.

Brown widows and false widows have bites that can cause local pain but are not considered very dangerous, sort of like a wasp sting. Black widow species have more potent venom, but are not aggressive, and a healthy adult most likely wouldn’t need medical attention. The only issues arise when bites occur on people who are very young, elderly, immunocompromised, or have an allergy.

True widows will have the red or orange hourglass or similar markings on the underside of their abdomen, and false widows do not!

False black widow, Steatoda grossa, found in many parts of the world:

Underside:

Their color and markings can vary pretty hugely between individuals, especially depending on life stage. You can view the variety here.

Photos by leeroyhamilton96, sarinozi, and mike68lusk

Brown widow, Latrodectus geometricus, found throughout the southern half of the US and a bunch of other countries as well:

Browse more photos for color variation here!

Photos above by wayne_fidler

Western black widow, Latrodectus hesperus, found in the US west of the Mississippi:

Juvenile:

As you can see, these also have a big range of color patterns from juvenile to adult and are often confused with brown widows because of it. They have the typical hourglass on the underside of their abdomen, but sometimes the two halves of the hourglass don’t connect. You can view lots of photos of them here!

Photos above by damontighe, levfrid, and merav

And the southern black widow, Latrodectus mactans, found mostly in the southeastern US, west through Texas and down into Mexico, but can sometimes be found further west:

Juvenile:

This species also has a lot of color variation from juvenile to adult but again, it will have the red or orange hourglass. You can view more photos of them here.

Photos by fiddleman, greglasley, and marp-issa

The western and southern black widows are not the only black widow species, but they are the most common species in the US, and their venom has about the same potency.

Keep in mind that these spiders are not aggressive and will only bite to defend themselves, usually if they’ve accidentally ended up on your body or in your clothes and feel threatened and just want to get away!

Hope that was helpful :)

[h0m0less]

some women are so camera shy (Widow Spider species, likely Latrodectus geometricus)

[plumpengu]

omg i love bug train! in order of appearance (left to right) we got:

Monk skipper (Asbolis capucinus)

Brown Widow (Latrodectus geometricus)

Diaprepes root weevil (Diaprepes abbreviatus)

Little blue dragonlet (Erythrodiplax minuscula)

and (a personal favorite of mine!) Polistes dorsalis

these are all kinda old findings since i havent been able to get out in a while, but still fun to share!

Hey @willyeeton and everyone else, I was out today and found a lot of remains of stag beetles! It’s the largest beetle in Europe!

Click for better quality

Oh and cw bugs and dead things if anyone needs it

[abartbyalexst]

Black widow spider - Oil Paint

Latrodectus is a broadly distributed genus of spiders with several species that are commonly known[citation needed] as the true widows. This group is composed of those often loosely called black widow spiders, brown widow spiders, and similar spiders. However, the diversity of species is much greater. A member of the family Theridiidae, this genus contains 34 species, which include several North American "black widows" (southern black widow Latrodectus mactans, western black widow Latrodectus hesperus, and northern black widow Latrodectus variolus). Besides these, North America also has the red widow Latrodectus bishopi and the brown widow Latrodectus geometricus, which, in addition to North America, has a much wider geographic distribution. Elsewhere, others include the European black widow (Latrodectus tredecimguttatus), the Australian redback black widow (Latrodectus hasseltii) and the closely related New Zealand katipō (Latrodectus katipo), several different species in Southern Africa that can be called button spiders, and the South American black-widow spiders (Latrodectus corallinus and Latrodectus curacaviensis). Species vary widely in size. In most cases, the females are dark-coloured and can be readily identified by reddish markings on the central underside (ventral) abdomen, which are often hourglass-shaped. These small spiders have an unusually potent venom containing the neurotoxin latrotoxin, which causes the condition latrodectism, both named after the genus. Female widow spiders have unusually large venom glands, and their bite can be particularly harmful to large vertebrates, including humans. However, despite their notoriety, Latrodectus bites rarely cause death or produce serious complications. Only the bites of the females are dangerous to humans.

[cyanocoraxx]

black widow spiders

there are 31 recognised species commonly referred to as "widow spiders." widows are distributed worldwide, ranging from north america, africa to australia, and have a notorious reputation for their medically significant bites and "aggressive" nature. many of these spiders should in fact be described as shy and defensive rather than aggressive and evil - in most cases, poking one with your finger isn’t enough to warrant a bite, rather, the spider will often run away, play dead or flick strands of silk in your direction (don’t try that at home tho.) when bites do happen, they tend to be due to the spider being squished or pinched across the entire length of its body, which can happen by accident if it becomes trapped in clothing or when someone tries to kill the spider deliberately. nowadays this is very rarely fatal to humans, and 75% of envenomations cause localised pain and nothing more, the rest being “dry bites” where no venom is involved. it should also be noted that only adult females will bite - spiderlings and males do not.

latrodectus mactans, southern black widow

southern black widows are the epitome of the “classic” widow spider, distributed across north america in almost every state. adult females are 25-35mm and are a glossy jet black colour with a bright red hourglass marking on the underside of the abdomen and a red spot above the spinnerets. outdoors, black widows spin their webs in woodpiles, rubble piles, around stones, hollow stumps and in rodent burrows. indoors, they prefer privies, sheds, garages and crawl spaces, where they are unlikely to be disturbed. most bites from the southern widow occur when a person touches the web or accidentally traps the spider against their skin.

latrodectus bishopi, red widow

the red widow is endemic to central and southern florida. it is restricted to sand-pine scrub, characterised by dry sand dunes dominated by sand pine trees. within this habitat, the red widow makes webs in palmetto bushes at heights of 30cm or higher above the ground. confinement to this unique habitat contributes to the spider’s rarity, and its web further conceals it - the species builds funnel-shaped retreats inside unopened palmetto leaves, with only a loose tangle of threads between the tips of the leaves giving any indication of its presence. it’s believed to be venomous like the other widow species, but no bites have ever been recorded in medical literature because they prefer to live far away from humans.

latrodectus geometricus, brown widow

brown widows have a pantropical distribution, found in south africa, australia, south america, afghanistan, japan, thailand and even more areas. in these areas, brown widows seem to prefer secluded, protected sites to build their webs, including empty containers, mailboxes and garages. they tend to choose places that are more exposed than those that the black widow would choose and hence are more likely to encounter humans by accident, but fortunately, it was found in research that they are less venomous than black widows. researchers have even suggested that the brown widow may be displacing black widows by outcompeting them for food and territory. they are highly variable in colour, coming in white, grey, light brown and black forms, and this colour is determined by the colour of their surroundings at the time of molting.

latrodectus hasseltii, redback spider

redbacks are widespread across australia but also distributed in southeast asia and new zealand. individuals have been reported in japan, england, the united arab emirates and iran. they prefer drier habitats ranging from slerophyll forest to harsh deserts, but have become more common in urban areas, especially in brisbane, perth and alice springs. they build webs in dry, dark sheltered sites such as amongst rocks, in logs, old tyres, sheds and empty bins. redbacks are capable of surviving temperatures below freezing to over 40C and can survive over 300 days without eating. although they are responsible for many bites in australia each year, the introduction of antivenom now means that fatalities are extremely unlikely.

latrodectus tredecimguttatus, european widow

this species is commonly found throughout the mediterranean region, ranging from southern iberia to southwest and central asia. the body is black in colour with thirteen spots on the abdomen, which can be red, yellow or orange. primarily living in steppes and open grasslands, the european black widow can be a significant issue in areas where grain is harvested by hand - bites can occur when the spider’s web is destroyed or otherwise disturbed.

latrodectus katipo, red or black katipo

the katipo is an endangered species native to new zealand. its name is derived from the māori word katipō, meaning "night-stinger." two forms have been identified - red and black. both forms are found in sand dunes close to the seashore where they spin irregular tangled webs amongst dune plants. driftwood, stones, empty cans and bottles. these shy, non-aggressive spiders are threatened with extinction due to habitat loss and coastal dune modification resulting from urban development, recreational activities and driftwood collection.

[joecowtoy]

The Brown Widow (Latrodectus geometricus), a close relative to the Black Widow. . #brownwidow #brownwidowspider #hourglass #spider #creeper #web #desert #olympusem5 #olympusomd #olympusomdem5 #macro #rokkor50mm_macro (at Tuacahn Center for the Arts)

[egreed]

Me: *about to make a post about how I love spiders*

Spider: *drops down from the ceiling*

Me: Ya bitch I'm talkin about you.