Northern ribbon snake.

 Rondeau Provincial Park, Ontario, Canada, May 21, 2015.

The lines on the log are from the emerald ash borer that eventually kills the ash tree.

Thamnophis saurita septentrionalis,

The emerald ash borer is an invasive insect that was first discovered in Ontario in June 2002.

The beetle likely crossed into Ontario at Windsor after establishing in the Detroit area, where it probably arrived in wood packaging or pallets.