Genesis 3:14 (NET) The LORD God said to the serpent, “Because you have done this, cursed are you above all the wild beasts and all the living creatures of the field! On your belly you will crawl and dust you will eat all the days of your life."
Part of God's judgment upon the serpent was that he (and his seed) would eat dust for all the days of his life. John Sailhammer notes that eating dust in the Bible has the idea of total defeat. Thus, every time you see a snake crawling on the ground, be encouraged. From the moment his rebellion started in the garden, he was already defeated. And one day, his defeat will be complete.