Latrodectus variolus

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Latrodectus variolus
Latrodectus variolus (Northern Black Widow), F Theridiidae.jpg
Northern Black Widow - Latrodectus variolus, Julie Metz Wetlands, Woodbridge, Virginia - 15471199337.jpg
Male (with damaged legs)
Scientific classification edit
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Theridiidae
Genus: Latrodectus
L. variolus
Binomial name
Latrodectus variolus

Latrodectus variolus, the northern black widow spider or northern widow, is a species of spider in the genus Latrodectus of the family Theridiidae. The population is closely related to the southern black widow, Latrodectus mactans, and the western black widow, Latrodectus hesperus, of the genus.[citation needed]

It is commonly found in Middle Atlantic states (New Jersey, Delaware, Maryland) of the United States. During the April–May mating season, it can travel north along the coast as far as Massachusetts. It is also found in Connecticut in the late summer, and rarely, in southern Ontario and southern Quebec,[2] Canada, Michigan,[3] and at least as far northwest as parts of Wisconsin.[4]

A bite may cause latrodectism, and requires medical attention in the case of increasingly severe discomfort or spreading local redness accompanied by severe pain.[5] The LD-50 has been measured in mice as 1.20–2.70 mg (0.019–0.042 gr); each spider contains about 0.254 mg (0.0039 gr) of venom.[6]

Unlike for the related Latrodectus mactans, as of 2015 no antivenom was available.[citation needed]


  1. ^ "Taxon details Latrodectus variolus Walckenaer, 1837", World Spider Catalog, Natural History Museum Bern, retrieved 2016-04-26
  2. ^ Wang, Yifu; Casajus, Nicolas; Buddle, Christopher; Berteaux, Dominique; Larrivée, Maxim (2018). "Predicting the distribution of poorly-documented species, Northern black widow (Latrodectus variolus) and Black purse-web spider (Sphodros niger), using museum specimens and citizen science data". PLOS ONE. 13 (8): e0201094. doi:10.1371/journal.pone.0201094. PMC 6082516. PMID 30089136.
  3. ^ [1]
  4. ^ [2]
  5. ^
  6. ^ McCrone, J.D. (December 1, 1964). "Comparative lethality of several Latrodectus venoms". Toxicon. 2 (3): 201–203. doi:10.1016/0041-0101(64)90023-6. PMID 14298228.

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