Funny you mention using Castrol Super Clean ... I thought I was the only one ! Its the best bug spray i've ever found ... It'll put a big spider legs up quicker than any bug spray i've found.
We have tons of Black Widows in So Calif. I could go out in my back yard right now and find a half dozen of them easily. They aren't usually an agressive spider, but if you put your hand near one by accident they will put a hurtin on you !
You can always tell a Black Widow web, its a tangled mess with no pattern.
If you touch it you'll know in an instant because it feels like your tugging on little steel strands ... its considered pound for pound one of the strongest substances there is. In fact Northrop used the stuff for cross hairs on bombsites during WWII
My God i'm sounding like an episode on the Discovery Channel !
