Black Widow females have a very distinctive look: a black, shiny body with bold red spots. The web appears tangled & unstructured.
The female Black Widow in the photo was hanging out on the inside of an infrequently used rusty bucket that had been turned upside down to prevent it from collecting water that would provide a breeding ground for mosquitoes. Instead, we apparently provided good habitat for a venomous spider.
The upperside has some red spotting:
Ventral view with the classic red hourglass:
The males look very different than the females (and are also smaller):
2013 seems to have been a banner year for Black Widows here. Previously, we saw one maybe every year or two, but in 2013 we observed numerous specimens. We pretty quickly learned that chaotic-looking webs were a warning sign that one might be around. The chaotic web (see left part of the photo below) was what drew my attention to this egg sack on a ladder rung. There was a female behind the egg sack (out of view in this photo). The ladder had recently been brought into our bedroom, but it didn’t stay there long! Photo was taken outdoors.