Latrodectus variolus

Latrodectus variolus
	Female
	Male (with damaged legs)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
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 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]}