Quit killing snakes. Unless it's in your house, or has your kid in it's mouth, let them be.
I agree to an extent...had to learn the hard way though.
I was always told non-poisonous snakes (especially black snakes here) will keep the poisonous ones away. I never believed it and killed all the snakes I came across, killed 5 black snakes in 3 days when the squirrels were having young (one black snake was over 8' long).
Didn't see any snakes for about a year, then one day my Dad and I had to put his old truck in the shop (it was going to hail) at the time the motor was out and we had to push it in. Got the truck in there and my Dad went to grab what he thought was a leaf sticking in the cowl area, and pulled his hand back quick. Threw the hood up and there was a copperhead laying in the cowl area, it was his head sticking up on the windshield.
We had a heck of a time getting that thing out of the fender, but eventually got it out and shot it.
Now I don't kill the black snakes or garter snakes and haven't seen any copperheads since...in fact I just ran across a 5' black snake crossing the road in the turn right before my driveway about an hour ago.
Ted, remind me next gtg to tell the water snake story...it takes me too long to type it here.