20 February 2024

Members of the genus Latrodectus are commonly called the Widows. These spiders are in the family Theridiidae, the cobweb spiders. They spin tangled webs in dark and enclosed spaces such as under logs, in mammal burrows or even inside buildings. Females are larger than males and sometimes do eat the males after mating (though that is not always the case).

While most spiders are venomous, the venom of these spiders is considered medically significant. Their venom contains neurotoxins specific to these spiders (latrotoxins). A bite may result in localized swelling, pain, muscle cramping, vomiting and excessive sweating with symptoms lasting a few days. Thankfully, these spiders are quite rare in Minnesota and they are not aggressive. The chance of you finding one and then being bitten by it would be extremely rare. Information about treatment can be found on the Mayo System website: https://www.mayoclinic.org/diseases-conditions/spider-bites/symptoms-causes/syc-20352371.

There's some great information about this genus and distinguishing between species on BugGuide: https://bugguide.net/node/view/1999. I won't repeat all that information in detail here.

Three of the four Latrodectus known to occur in Minnesota typically arrive as stowaways in greenhouse plants, produce, furniture, etc. from locations further south. I know of no breeding populations of them in the state. The accidental species are L. geometricus/Brown Widow, L. hesperus/Western Black Widow and L. mactans/Southern Black Widow.

Latrodectus variolus or Northern Black Widow should be the only native species but this species' distribution in Minnesota is poorly understood. While I am still trying to determine its full range, its current known range is limited to the southeastern counties of Houston, Fillmore, and Winona. People living in the counties adjacent (Mower, Olmsted, Wabasha) should keep an eye out for their first county records. I have not seen this species personally but communication with those who have have found it in prairies, in gopher holes and inside of sheds.

Happy spidering!