Latrodectus variolus

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Latrodectus variolus
Latrodectus variolus (Northern Black Widow), F Theridiidae.jpg
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Araneae
Family: Theridiidae
Genus: Latrodectus
Species: L. variolus
Binomial name
Latrodectus variolus
Walckenaer, 1837

Latrodectus variolus, the Northern black widow spider or Northern widow, is a medically important spider species of the Latrodectus genus in the Theridiidae family. The population is closely related to the Southern Black Widow, Latrodectus mactans, and the Western Black Widow, Latrodectus hesperus, of the genus.

It is commonly found in Middle Atlantic states (New Jersey, Delaware, Maryland). During the April–May mating season, it can travel north along the coast as far as Massachusetts. It also occurs in Connecticut in late summer. It is found, rarely, in southern Ontario, Canada.

A bite may cause latrodectism, and requires medical attention in the case of increasingly severe discomfort or spreading local redness accompanied by severe pain.[1] 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.[2]

Unlike for the related Latrodectus mactans, as of 2015 no antivenin was available.


  1. ^
  2. ^ 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. 
  • Platnick, N. I. 2008. Theridiidae The World Spider Catalog, version 9.0. American Museum of Natural History.

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