Species of Latrodectus – The Widow Spiders

    • Scientific Name: Latrodectus spp.

    • Subspecies: Various

    • Common Name(s): Various but all are widow spiders.

    • Family: Theridiidae

    • Max Size: Up to approx. 2 inches

    • Antivenom Code(s): IAmNIA06, IAuCSL05, IAmMSD01

    • Geographical Range: Worldwide

    • Conservation Status: Stable


The Black Widow Spider is one of the most famous spiders in the world. They are feared by many for their deathly appearance and their dangerous reputation. However, I hope that you will have a different but healthy view of black widow spiders and their related species by the end of this article as they are amazing creatures.


The Black Widow Spider and other species of widow spiders come from the genus Latrodectus. The easiest way to identify Widows Spiders, although it is not always reliable, is by their notorious hourglass shape on the underside of their abdomen. 


The hourglass of the Black Widow Spider is notorious throughout the world, giving a feeling that it is only a matter of time before one dies. However, widows spiders most likely will not kill you if you are a healthy adult, but it will be a very unpleasant experience. The people who are at most risk for death are children and the elderly.

“The prime example of a spider dangerous to humans is certainly the black widow spider, Latrodectus mactans, from the family Theridiidae (fig. 3.7a, b). The bite itself is not particularly painful and often is not even noticed (Maretic, 1983, 1987). The first real pain is felt after 10—60 minutes in the regions of the lymph nodes, from where it spreads to the muscles. Strong muscle cramps develop, and the abdominal muscles become very rigid (this important diagnostic feature). Another typical symptom is a contorted facial expression, called facies Iatro-dectismi, which refers to a flushed, sweat-covered face, swollen eyelids, inflamed lips, and contracted masseter muscles. If the breathing muscles of the thorax become affected, this can eventually lead to death. Besides the strong muscle pain, the black widow spider venom (BWSV) also elicits psychological symptoms, which range from anxiety feelings to actual fear of death. Apparently the toxin can pass the blood—brain barrier and directly attack the central nervous system. Without any treatment the symptoms will last for about 5 days, and a complete recovery may take weeks. About 80 years ago, lethality was 5% in the United States (Thorp and Woodson, 1945), but since 1970 it is less than 1% (Zahl, 1971).” (1:54)

The best treatment against a bite from a black widow is a combination of calcium gluconate with opioids and benzodiazepines plus an antivenom (McCrone and Netzloff, 1965; R. F. Clark, 2001). Calcium causes the pain to subside quickly, and the antidote binds to the toxin. The patient feels relieved within 10—20 minutes and will recover within a few days (isbister and Gray, 2003). The venom (BWSV) is a neurotoxin that affects the neuromuscular endplates (fig. 4.30b) but also affects synapses in the central nervous system. The synaptic vesicles become completely depleted) causing a permanent blockage of the synapse (Clark et al., 1972; Gnffiths and Smyth, 1973; Tzeng and Siekevit.z, 1978;”

The venom of some, if not all Latrodectus species is considered medically significant and is a neurotoxin. The results I found for species of latrodectus for the LD50 ranged from about 1.23 to 0.26 mg/kg. That includes different species. The LD50 of the Southern Black Widow (latrodectus mactans) is around 0.26 mg/kg, according to an article in the Journal of toxicology. Clinical toxicology (2), which is found here (I kept finding different numbers, which is understandable because the LD50 only gives a rough estimation of how toxic a venom is, and that is for mice, not humans; there are many factors involved). To understand venom and what is the LD50, check out our page called What is Venom? 

Here is a quote from the Journal of Arachnology, Black widow spiders, Latrodectus spp. (Araneae: Theridiidae), and other spiders feeding on mammals by Martin Nyffeler1 and Richard, speaking about the toxicity of some species of latrodectus

“Venom from the Eurasian L. tredecimguttatus has an LD50 of 0.013 mg of dried gland extract per mouse translating to an overall LD50 of 0.9 mg/kg (Bettini & Marioli 1978). It is estimated that the venom of one spider had enough potency to kill 40 mice (Maretic´ & Lebez 1979). Venom from four species of Argentinian Latrodectus spiders produced LD50 values ranging from 3.1 to 22.5 lg/animal in 18–22 g CF-1 mice (de Roodt et al. 2017) translating to approximately 0.15 to 1.23 mg/kg for the average 20 g mouse. Using whole gland extract, D’Amour et al. (1936) estimated the LD50 in rats as 0.032 mg which they considered as 25% of the widow’s venom quantity. As they used rats of 50 to 60 g weight, this would translate to an LD50 of 0.53 to 0.64 mg/kg. These LD50s are similar to that for American rattlesnakes (Glenn & Straight 1978). – ref

While that seems all bad, here is the good news: this is a quote from the National Center for Biotechnology Information regarding the likely hood of recovery if bitten by a Black Widow:

“The prognosis for black widow bites is good. Most pain and systemic symptomatology are self-limited. Although patients may encounter long-term pain or muscle spasms after black widow bites, this phenomenon is rare. Similarly, systemic toxicity, including abdominal pain and autonomic dysfunction, is usually temporary. Recovery is usually complete within 24 to 48 hours. Finally, administration of anti-venom with a subsequent anaphylactic reaction is, as with most anaphylactic reactions, rare and usually a transient condition. Most patients can, and should, expect a full recovery after black widow envenomation.” – see reference under prognosis

However, have people died from Black Widow bites? Yes, so you need to be seriously careful with Widow Spiders. To read about black widow spider bites cases, click here.

The following is a great video of a Black Widow Spider biting someone and how they reacted to the venom, even without going to the hospital.



You probably wont need to purchase your own antivenom for widow spiders because most hospitals in developed countries will have it for local species (assuming you are collecting local species).


    • Antivenom Code: IAmNIA06

    • Manufacturer: Instituto Nacional de Produccion de Biologics

    • A.N.L.I.S.

    • Phone: ++54-11-4303-1806 (to 11)


    • Antivenom Code: IAuCSL05

    • Antivenom Name: Red-backed spider antivenom

    • Manufacturer: CSL Limited

    • Phone: ++61-3-9389-1911


    • Antivenom Code: IAmMSD01

    • Antivenom Name: Antivenin ( Latrodectus mactans )

    • Manufacturer: Merck Sharp and Dohme International

    • Phone: ++1-800-396-6250


Black Widow Spiders are slightly nervous creatures, but not aggressive. They would probably only bite if highly provoked, for example, pinning one with your hand.


Species of the genus Latrodectus are found all over the globe, but in the United States, we have the Latrodectus mactans (The Southern Black Widow), hesperus (The Western), variolus (The Northern), geometricus (The Brown), and bishopi (The Red). I tend to see Widows Spiders in urban areas. They seem to prefer dry places in general, and while there are exceptions, you do not encounter North American species in extremely damp areas, i.e., a swamp. However, brown widows are not originally native to the United States, and I have seen them in damp areas.

The following is a quote from, which is “a cooperative venture of the University of Florida’s Entomology and Nematology Department and the Florida Department of Agriculture and Consumer Services’ Division of Plant Industry.” The quote refers to where Widow Spiders are typically found:

“Typical 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, their web can be found several meters from the ground (Kaston 1938).”

A personal example is that I encountered a Latrodectus geometricus in my front yard. I was not anticipating this at all when I first stumbled upon her web; the place where she created her web is quite busy with people and cars, so it was a surprise. She was dwelling in a red broken off pipe sticking out of the ground.

An interesting example to me was I found at least 30 Brown Widows (I counted) on the back side of a Costco in the direct Sunlight. It was super hot and the medal walls of Costco were extremely hot to touch, so for the spiders to thrive here was fascinating.


    • Longevity: Up to a year or more (2)

    • Communal: No

    • Diet & Feeding: I find that they eat crickets very well. I had problems with cockroaches because they tend to hide, and it takes a long time for the spider and the cockroach to meet, so I don’t recommend them. 

    • Enclosure: Widows are wonderfully simple creatures to care for. I house my Widows in these enclosures from the Container Store (Not an Affiliate Link). However, I like the idea of something bigger for them as I feel they are still too small and hard to work with. They are fine, especially if you keep many Widows, but I prefer something larger for them to build greater webs, and so that I do not disturb their webs each time I open the cage. They are about 6 and 1/2 inches tall, 3 and 1/2 inches wide and deep. I melt holes in the top with a tool for woodworking. However, I want to try drilling next time as I think melting does not have a clean look.

    • Lighting: Direct forms of lighting is unnecessary and may cause stress to the spider. However, often you will find widow spiders in direct sunlight waiting for their prey.

    • Temperature: High, but will be fine in room temperature.

    • Humidity: Widows do not need a water bowl; however, I recommend lightly misting them about every two weeks. Much water is bad for them, but misting them occasionally is a good idea.

    • Water: Not needed

    • Decor: Widows make webs, and need things to climb to make their webs. Use preferably sticks of some kind. They are thin and do not get in the way of seeing the spider. 

  • Substrate: I fill the bottom with animal safe woodchips, which can be purchased at most pet stores or easily ordered online. Lighter colors like the woodchips seen above help the spiders stand out; avoid similar colors to the spiders for display reasons. I now avoid using coconut husk because of it easily molds (at least for me), and its dark color makes it hard to see the spider. Notice the picture below of the spiders for an example of the substrate and the clarity.
  • When they are babies, also called spiderlings or as collectors call them; “slings,” the care is the same just smaller; have a small container and give them pinhead crickets or flightless fruit flies and watch them grow. Make sure the cage is small, so their prey finds them more frequently.

How to Acquire a Species of Letrodectus

Widows, at least in the United States, are common, search around old houses, garages, brick piles, etc. However, for the U.S., you are limited to the species mentioned earlier: the Latrodectus mactans (The Southern Black Widow), hesperus (The Western), variolus (The Northern), geometricus (The Brown) and bishopi (The Red).

Most people do not sell them, and you probably won’t see them in a regular pet store. However, there are people online who sell them. Just Google “Black Widows for sale” or the certain species you want, and things should come up. If you don’t find want you want, I encourage you to go on to Instagram and search for the species you want. Look for accounts of people who have lots of spider pictures and ask them if they sell or import spiders or where they got their spiders.

Estimated Price: The price for Black Widows is about $15 to $30, depending on the species and size; exotics might be more expensive. Shipping for me has consistency been $45 for overnight shipping, which is typical for shipping animals as it is safer for the animal.

Taxonomic Classification

Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Family: Theridiidae
Genus: Latrodectus
Species: See List

The Spiders of the latrodectus genus are quite beautiful. I encourage you to look up the different species listed below as well as viewing the gallery at the end of this article because they are truly beautiful creatures. 

The following is the list of accepted species according to the World Spider Catalog as of 2019:

    1. Latrodectus Antheratus

    1. Latrodectus Apicalis

    1. Latrodectus Bishopi

    1. Latrodectus Cinctus

    1. Latrodectus Corallinus

    1. Latrodectus Curacaviensis

    1. Latrodectus Dahli

    1. Latrodectus Diaguita

    1. Latrodectus Elegans

    1. Latrodectus Erythromelas

    1. Latrodectus Geometricus

    1. Latrodectus Hasselti

    1. Latrodectus Hesperus

    1. Latrodectus Hystrix

    1. Latrodectus Indistinctus

    1. Latrodectus Karrooensis

    1. Latrodectus Katipo

    1. Latrodectus Lilianae

    1. Latrodectus Mactans

    1. Latrodectus Menavodi

    1. Latrodectus Mirabilis

    1. Latrodectus Obscurior

    1. Latrodectus Pallidus

    1. Latrodectus Quartus

    1. Latrodectus Renivulvatus

    1. Latrodectus Revivensis

    1. Latrodectus Rhodesiensis

    1. Latrodectus Thoracicus

    1. Latrodectus Tredecimguttatus

    1. Latrodectus Variegatus

    1. Latrodectus Variolus

    1. Latrodectus Walckenaer

(This List of Species is subject to change)

“Where there is love there is life.” – Mahatma Gandhi

Works Cited & Further Reading

    1. Biology of Spiders, third Edition by Rainer F. Foelix