Northern Black Widow

Theridiidae, which is the family of cobweb spiders, includes the Northern Black Widow (Latrodectus variolus). In addition to being widely dispersed throughout the eastern and northern United States as well as southern Canada, it is one of the most venomous spiders in Illinois. Male northern black widows are 4 to 5 millimeters long, while females are between 9 and 11 millimeters long. They resemble typical black widows in appearance, with the exception of a red hourglass-shaped mark on their abdomens. The hourglass is rarely whole, though, which makes this black widow distinct from other black widows.

The venom that can cause latrodectism is carried by northern black widows. When bitten, people frequently experience pain, perspiration, nausea, and stiffness in their muscles. Their bite can occasionally be lethal. That said, most people that die from northern black widow bites are either very young or severely immunocompromised.