Summary
Southern females have a complete red hourglass and no dorsal markings. Northern females have a broken (two-triangle) hourglass and a row of red dorsal spots down the abdomen.
Diagnostic traits
| Trait | Northern Black Widow | Southern Black Widow |
|---|---|---|
| Hourglass | Two separated triangles (broken) | Complete, joined |
| Dorsal abdomen | Row of red spots | Plain glossy black |
| Range | Northeast and upper Midwest | Southeast, Gulf, Southwest |
The bottom line
At-a-glance comparison
| Northern Black Widow | Southern Black Widow | |
|---|---|---|
| Scientific | Latrodectus variolus | Latrodectus mactans |
| Family | Theridiidae | Theridiidae |
| ♀ body | 9–11 mm | 8–13 mm |
| Leg span | 25–38 mm | 25–38 mm |
| Range | 18 U.S. states | 23 U.S. states |
| Medical | Medically significant | Medically significant |