I live in the Bay Area in a warmer microclimate. We've got widows, sizable orb weavers, and supposedly tarantulas (although I've never seen one and have my doubts). I've twice been bitten by something while either under my house or in my basically wild yard and gotten nasty infection. One bite was on my elbow and become necrotic. It was treated only with antibiotics. It now looks like I took a bullet. The other was on my neck and required surgery. Although I had some mild symptoms suggestiong a black widow bite, they were also symptoms of infection, so the doctor concluded it was not a widow that bit me. Anything that can pierce the skin can give you a nasty infection.