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Southern Black WidowLatrodectus mactans

Every figure, record and mechanism on the Southern Black Widow profile was written from a source, and this is the working table behind it: 40 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Eiden & Kaufman 2013

Eiden & Kaufman (2013). Southern black widow Latrodectus mactans (Fabricius) (Arachnida: Araneae: Theridiidae). EDIS.

The page saysShiny black spider
The source saysis a shiny black spider
The page saysNot Evaluated
The source saysThe Southern black widow spider, Latrodectus mactans (Fabricius), is a venomous spider found throughout the southeastern United States.Note: GBIF's copy of the Red List returns NOT_EVALUATED for Latrodectus mactans (Fabricius, 1775), usage key 2157949, checked 2026-09-27 (api.gbif.org/v1/species/2157949/iucnRedListCategory). Crossref has no Red List assessment DOI for this name either.
The page saysOften in wood and rock piles, rodent burrows, and hollow stumps outdoors, or sheds, garages, basements, and outhouses indoors
The source saysTypical outdoor habitats in which spiders are often found include wood and rock piles, rodent burrows, and hollow tree stumps. Indoor habitats include outhouses, garages, sheds, and basementsNote: stats.habitat; the range half of this field (north to Ohio, west to Texas) is the same-source claim below
The page saysnorth to Ohio and west to Texas
The source saysthe Southern black widow is found in the southeastern region and has been found as far north as Ohio and as far west as TexasNote: stats.habitat, range clause
The page saysFlies, crickets, grasshoppers, moths, beetles, and other arthropods trapped in its web
The source saysWidow spider diet includes a wide range of insects such as flies, crickets, grasshoppers, moths, beetles, and various other arthropods that become trapped in the webNote: stats.diet; dropped ADW's old chilopods/scorpions since EDIS (current) lists centipedes and scorpions as known predators of the species, not prey
The page saysis a shiny black spider
The source saysis a shiny black spider with a distinctive red hourglass on the abdomen
The page saysfound across the southeastern United States, its range reaching as far north as Ohio and as far west as Texas
The source saysthe Southern black widow is found in the southeastern region and has been found as far north as Ohio and as far west as Texas
The page saysa body about 1.25 cm (0.5 in) long, typically 3.75 to 5 cm (1.5 to 2 in) including the legs
The source saysFemales are typically 3.75 to 5 cm long including the leg span, while their bodies are 1.25 cm long.Note: imperial conversions are the page's own (1.25 cm = 0.5 in; 3.75-5 cm = 1.5-2 in); reviewer changed 'a leg span of' to 'including the legs', since the source's 3.75-5 cm is total length with legs, not a leg span
The page saysMales are smaller, typically with a body just 0.6 cm long, and lack the female's hourglass
The source saysMale Southern black widows are smaller, typically with a 0.6 cm long body (Mote and Gray 1935). Male Southern black widows lack the characteristic hourglass of the female
The page saysFemales typically live around 1.5 years; males survive just two to five months
The source saysThe female Southern black widow typically lives an average of 1.5 years while the male survives between two to five months.
The page saysBoth primarily inhabit low-lying areas, and are often found in wood and rock piles, rodent burrows, and hollow stumps outdoors, or in sheds, garages, basements, and outhouses indoors
The source saysTypical outdoor habitats in which spiders are often found include wood and rock piles, rodent burrows, and hollow tree stumps. Indoor habitats include outhouses, garages, sheds, and basements (D’Amour et al. 1936). Although they primarily inhabit low-lying areas
The page saysThe venom contains the neurotoxin alpha-latrotoxin.
The source saysWidows have potent venom, which contains the neurotoxin alpha-latrotoxinNote: EDIS species account; its sentence is about 'widows'
The page saysThe web is built in an erratic manner with no distinguishable pattern
The source saysBlack widow webs are constructed in an erratic manner without a distinguishable pattern (Mote and Gray 1935).
The page saysFlies, crickets, grasshoppers, moths, beetles, and other arthropods become trapped in it.
The source saysWidow spider diet includes a wide range of insects such as flies, crickets, grasshoppers, moths, beetles, and various other arthropods that become trapped in the web
The page saysWidow spiders got their name from the belief that females kill and eat their mates after mating, but that was mainly observed in crowded laboratory conditions.
The source saysWidow spiders received their name from the belief that they would kill and consume their mate following copulation. However, the practice was mainly observed in laboratory settings under crowded conditions.
The page saysIn natural settings, it is believed to have more to do with the male's physical inability to escape than with the female's interest in eating him.
The source saysIt is believed that sexual cannibalism within the widow species in natural settings is more associated with the male’s physical inability to escape rather than the female’s interest in consuming him
The page saysIn 2010, people in the United States self-reported 2,168 black widow bites, and 892 of those cases were treated in health care facilities. That year's survey recorded no deaths, and death from a black widow bite is rarely reported. Patients usually recover within 24 hours after treatment, or in 3 to 5 days without supportive care.
The source saysIn 2010, there were 2,168 self-reported black widow bites reported in the United States, with 892 cases treated in health care facilities (Bronstein et al. 2011). Death due to a black widow bite is rarely reported (Timms and Gibbons 1986). In the 2010 survey, over 50% of reported cases occurred in patients over 20 years of age with no deaths (Bronstein et al. 2011). Patients usually recover within 24 hours following treatment or 3 to 5 days without supportive careNote: faq 1; US black widow bites of any species, so the question now asks about black widows generally
The page saysThe behavior was mainly seen in widows kept crowded together in the lab.
The source saysthe practice was mainly observed in laboratory settings under crowded conditionsNote: faq 2
The page saysIn the wild, the thinking is that it is linked more to a male being physically unable to get away than to any real interest on the female's part in eating him.
The source saysIt is believed that sexual cannibalism within the widow species in natural settings is more associated with the male’s physical inability to escape rather than the female’s interest in consuming himNote: faq 2; 'the leading idea' carries the source's 'It is believed'
The page saysTypically around 220, in a beige egg sac about 1 to 1.25 cm across.
The source saysThe female produces a beige-colored egg sac that is approximately 1.0-1.25 cm in diameter and typically contains around 220 eggsNote: faq 4
The page saysAfter an incubation of one month the spiderlings emerge
The source saysafter an incubation period of one month the spiderlings emerge from the egg sacNote: faq 4
The page sayswhite and without the hourglass or spots, and look more like adults with each molt.
The source saysSpiderlings are initially white and lack the hour-glass or spot patterns, but gain coloration and patterns more resembling adults with progressive moltsNote: faq 4
The page saysfor a spider whose cobweb is built in an erratic manner with no distinguishable pattern
The source saysBlack widow webs are constructed in an erratic manner without a distinguishable patternNote: vibe.reason mechanism, re-paired in wave 112 (screenshot test).

Source
02

Animal Diversity Web, University of Michigan

Latrodectus mactans. Animal Diversity Web, University of Michigan.

The page saysusually a red hourglass mark on the underside of the abdomen
The source saysUsually on the underside of the female's abdomen (venter) is a red hourglass mark
The page saysThe species averages about 1 gram.
The source saysAverage mass 1 gNote: ADW gives the mass unsexed, so the sentence is species scope rather than the female list it used to sit in
The page saysa mature male abandons his home and spends considerable effort finding a female
The source saysA mature male spins a small “sperm web” and deposits a small quantity of semen on it. He then charges his palps with the sperm, abandons his habitat, and spends considerable effort to locate a female of his species
The page saysThe spider has a row of strong, curved bristles on its hind legs, forming a comb, which it uses to fling silk over its prey.
The source saysThe spider has a row of strong, curved bristles on the hind pair of legs, which form a distinct comb. The comb is used for flinging silk over its prey.
The page saysIt then bites the prey and later drags it to its hub, or retreat, to be eaten.
The source saysthe black widow spider enswathes prey caught in its snare, bites it, and later drags it to its hub, or retreat, to be eaten
The page saysThe female hangs upside down in her web so that her red hourglass serves as a warning signal to predators.
The source saysthe female spider hangs upside down in her web so that her red hourglass mark serves as a warning signal to a predator

Source
03

Binder 1989

Binder (1989). Acute Arthropod Envenomation: Incidence, Clinical Features and Management. Medical Toxicology and Adverse Drug Experience.

The page saysvenom floods the nerve-muscle junction with acetylcholine and noradrenaline
The source saysaffecting the presynaptic motor endplate to allow massive noradrenaline (norepinephrine) and acetylcholine release into synapsesNote: tagline; reviewer dropped 'alpha-latrotoxin': Binder attributes the effect to 'the venom', not to a named toxin
The page saysVenom that acts on the motor endplate to allow a massive release of noradrenaline and acetylcholine, causing excessive stimulation and fatigue of the muscle.
The source saysaffecting the presynaptic motor endplate to allow massive noradrenaline (norepinephrine) and acetylcholine release into synapses causing excessive stimulation and fatigue of the motor end plate and muscleNote: stats.superpower
The page saysBlack widow venom acts on the presynaptic motor endplate, where nerve meets muscle, releasing massive amounts of noradrenaline and acetylcholine into the synapses.
The source saysBlack widow spider (Latrodectus mactans) envenomation is found throughout both the temperate and tropical latitudes, and is one of the leading causes of death from arthropod envenomations worldwide. The venom is highly neurotoxic, affecting the presynaptic motor endplate to allow massive noradrenaline (norepinephrine) and acetylcholine release into synapsesNote: blockquote; Binder names Latrodectus mactans; 'where nerve meets muscle' glosses 'motor endplate'
The page saysThe result is excessive stimulation and fatigue of the motor end plate and muscle.
The source saysrelease into synapses causing excessive stimulation and fatigue of the motor end plate and muscleNote: blockquote

Source
04

Grishin 1998

Grishin (1998). Black widow spider toxins: the present and the future. Toxicon.

The page saysIn the venom of a close relative, *Latrodectus tredecimguttatus*, researchers isolated alpha-latrotoxin, which provokes a massive transmitter release from vertebrate nerve endings, alongside five latroinsectotoxins that act on insects and one latrocrustatoxin active only on crustaceans
The source saysThe venom of the black widow spider Latrodectus mactans tredisimguttatus was found to contain a family of high molecular weight toxic proteins ... Along with the known alpha-latrotoxin, five latroinsectotoxins affecting the neurotransmitter release from presynaptic endings of insects and one latrocrustatoxin active only for crustaceans were isolated and studied in detail. Alpha-latrotoxin provokes a massive transmitter release from different nerve endings of vertebratesNote: other species: Grishin's spider is L. mactans tredecimguttatus (the source misspells it 'tredisimguttatus'), treated as its own species, L. tredecimguttatus, by Oldrati 2017 in this pack; the sentence names it and does not attribute the toxin set to L. mactans

Source
05

Oldrati et al. 2017

Oldrati et al. (2017). Peptidomic and transcriptomic profiling of four distinct spider venoms. PLOS ONE.

The page saysBy 2017 only 19 toxins had been identified from widow spider venom, and 10 of them are latrotoxins, large proteins more than 1,000 amino acids long that make up the major fraction of venom in this spider family
The source saysDespite its medical importance for humans, only 19 toxins from the Latrodectus venom have been identified and investigated thus far. Of these, 10 are large proteins (latrotoxins, length > 1000 amino acids), representing the major fraction of Theridiidae venom.Note: genus scope (Latrodectus) and family scope (Theridiidae), labelled as such; 'By 2017' dates the source's 'thus far'
The page saysIts heavy hitters are the latrotoxins, large proteins made of more than 1,000 amino acids. They are extremely neurotoxic to both insects and mammals through their activity at the presynaptic level, the sending end of a nerve connection, which leads to a massive release of neurotransmitter.
The source saysOf these, 10 are large proteins (latrotoxins, length > 1000 amino acids), representing the major fraction of Theridiidae venom. These toxins are extremely neurotoxic to insects and mammals due to their activity at the presynaptic level, which leads to massive neurotransmitter release.Note: faq 3; 'the sending end of a nerve connection' glosses 'presynaptic'

Source
06

Blackledge, Summers & Hayashi 2005

Blackledge, Summers & Hayashi (2005). Gumfooted lines in black widow cobwebs and the mechanical properties of spider capture silk. Zoology.

The page sayswidow cobwebs carry sticky "gumfooted" lines
The source sayswe use the sticky gumfooted lines of black widow cobwebsNote: the abstract names no species, so the sentence says 'widow cobwebs'

Source
07

Cabrera-Espinosa & Valdez-Mondragón 2021

Cabrera-Espinosa & Valdez-Mondragón (2021). Distribución y modelaje de nicho ecológico, comentarios biogeográficos y taxonómicos del género de arañas Latrodectus (Araneae: Theridiidae) de México. Revista Mexicana de Biodiversidad.

The page saysa study of females in Mexico recorded 40 distinct hourglass patterns, and the authors suggest Mexico may hold more widow species than are currently recognized
The source saysla descripción de la variación geográfica de los patrones de coloración dorsales y ventrales del opistosoma en hembras de L. mactans ... L. mactans presentó la mayor variación, registrando 40 patrones distintos. Dada la amplia variación morfológica y de patrones de coloración, la diversidad de especies en México podría estar subestimadaNote: Spanish: 'geographic variation of the dorsal and ventral colour patterns of the opisthosoma in L. mactans females ... L. mactans showed the greatest variation, recording 40 distinct patterns. Given the wide variation ... species diversity in Mexico could be underestimated'. The ventral pattern was described for L. mactans only, so the old 'most variable of the species compared' was cut

Source
08

Coticchio, Vetter & Cassill 2023

Coticchio, Vetter & Cassill (2023). Predation by the Introduced Brown Widow Spider (Araneae: Theridiidae) May Explain Local Extinctions of Native Black Widows in Urban Habitats. Annals of the Entomological Society of America.

The page saysIn Florida, where the native spider has been rapidly disappearing, cohabitation experiments found introduced brown widows were six times more likely to kill and eat southern black widows than to kill bold cobweb spiders.
The source sayswe report possible causes for the rapid disappearance of Florida’s Southern Black Widows ... In our experiments on cohabitation with neighbors, bold Brown Widows were six times more likely to kill and consume shy Southern Black Widows than bold cobweb spidersNote: experiments, not field observation: the old 'documented hunting in parts of Florida' is fixed
The page saysThe researchers suggest this predation is a significant factor in its local extinction from urban structures.
The source saysthis study is the first to suggest that aggressive predation by Brown Widows is a significant factor contributing to the local extinction of the shy Southern Black Widow in urban structures

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.