Neil: I know this is an old post about snakes, but I just thought of something that might help you. If you live in a rural area, not a subdivision, you could get some Guinea fowl and let them roam loose. Guinea fowl are an African bird that hates snakes. My wife raises different fowl and geese and the Guinea fowl are a unique bird. They will worry a snake and attack it until they kill it or drive it off. Guineas will also eat ticks, flies and other pest insects. They are good "watch dogs" and will raise a ruckus if an animal or person comes on the property. This is why I asked about if you lived in a rural location, the birds are noisy. A flock of them can sound like a rock band with badly tuned guitars. The trade off is a little noise but you will not have any snakes in your yard and fewer insects. They are not for everybody but if you like animals (MY wife too well) you might give them a try.