tips for repelling snakes (of all the county agriculture sites I searched, could not find one which endorsed any repellent and warned that use of repellents could actually harm your own pets or other wildlife).
http://www.allpestexpress.com/snakes.aspx
http://icwdm.org/handbook/reptiles/RattleSnakes.asp
http://www.rutherfordcounty.org/pets...nd%20Homes.pdf
While living down south the local zoo's information hand-out was that non-venomous snakes had round eyes as opposed to the elliptical eyes of venomous snakes. Not sure that info is entirely correct, but I'm not getting close enough to figure out eye shape.