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 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.

A bite may cause latrodectism. Reasons to go to the doctor after a spider bite include: Discomfort which is increasingly severe; Spreading local redness accompanied by pain.[1] 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. ^
  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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