Welcome to HTF Kim. All I know about snakes is red to yellow kill a fellow, red to black friend of jack, but that doesn't help for this snake. I find it a bit ironic that its on a welcome mat . A lot of snakes are tied to specific geographic areas. What state was this picture taken in?
Some kind of corn (rat) snake?
http://ndis.nrel.colostate.edu/herpatlas/coherpatlas/cdow_herpetofaunal_atlas_species_snake_elapheguttataemoryi.htm
Jay
p.s. any more bug/spider/snake threads?