Charactarized for their red, often hourglass like markings on their abdomens, the 4 species of Black Widows are highly venomous and very misunderstood.
Closely related to the Sidney Funnel Web, they are found in the very similar species of the "Southern Black Widow" (found in the Southeast US)the "Texas Black Widow" (found, well, in Texas), The "Northern Black Widow" (found in parts of Canada), and the "Western Black Widow" (found in California and its neiboring states). Gram for gram, their venom is deadlier than a cobra's, but a bite from one will probably not kill even withou antivenom due to the low quantities. The neurotoxin does, however, cause extreme illness without an antidote.
The photo below is of a Southern Black Widow.
Video
YouTube - Teen Wilderness Episode 1