I suspect the former as well.View attachment 119044
I wonder if they mean that the spiders they do have are not harmful to humans or very few of the spiders they do have are not harmful to humans. I assume, by the use of the comma in that sentence, it means the former. You wordsmiths out there may chime in.
Conversely, North Carolina has mosquitoes, plus snakes and spiders that ARE harmful to humans. On the plus side, the area I live in doesn't experience what I consider "winter weather", so I'm ok with the trade-off.