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 venomous 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 a common find in Middle Atlantic States (New Jersey, Delaware, Maryland). During the April–May mating season, it can travel northbound along the coast to as far as Massachusetts. It also occurs in Connecticut in late summer. It is also found, albeit rarely, in southern Ontario, Canada.

The bite is unpleasant, but not medically significant[1] unless it triggers an allergic reaction in the central nervous system. Seeing a doctor is usually suggested within a couple of hours after the bite or the symptoms appear. The LD-50 has been measured in mice as 1.80 milligrams (0.0278 gr) (with a confidence interval of 1.20-2.70), and each spider contains about 0.254 milligrams (0.00392 gr) of venom.[2]


  1. ^ Northern Black Widow Spider (Latrodectus variolus). 
  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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