In San Diego in... 2010? I remember seeing the population change. At first I thought the brown widows were just immature black widows, since they basically looked the same with lighter color and an alternating pattern. Read about the brown widows a few years later and it made sense.

FWIW, I fought them for years and finally gave up. I easily had over a hundred at any given time on my 6800 sq ft lot. Every night they'd spin webs between any vertical surface(i.e. my house, the fence, block walls) and the ground. In 16 years I never had an issue with bites to either me or my pets. I would clean the ones out that took residence under deck chairs, but that was about it. I never saw them inside the structure of my house, with the exception of < 1' from the garage door because there were gaps around it.

I had a healthy collection of daddy longlegs inside the garage. Not sure if they kept the widows in check.

The #1 enemy of widows is other widows, and they spread fast, so fighting them is often a losing battle.