Cobwebs spiders (family Theridiidae) are often housemates, wanted or otherwise. Even if you don’t see them, you may find their handiwork—messy, three-dimensional webs, with strands running in many different directions. The most famous in this group are the black widow spiders (genus Latrodectus), but most species are smaller, less boldly patterned, and comparatively harmless. This species is mostly found to the east of Rockies and typically in northern states, hence the name borealis, but has been found in southern ones over the last 50 years or so. Look for a reddish brown abdomen with a lighter “T” shaped mark at the front end. If you get a peek at the underside of the abdomen it is usually lighter than the upper.
Size: Females reaching a maximum size of about 7 mm
Photo by: Sarah Elizabeth on 7/20/22 in Arlee, MT