Yes, snakes do eat dust.
by Carl Wieland
First published in:
Creation Ex Nihilo 10(4):38,
September–November, 1988
In Genesis 3:14 we read, 'And the Lord God said unto the serpent... "upon your belly you shall go, and shall eat dust all the days of your life".' Since snakes do not really appear to eat dust, this has been taken as an example of either obvious metaphor (which seems reasonable) or an example of the Bible's propensity to error, depending upon one's bias.
In Micah 7:17 we read, '(The nations) shall lick the dust like a serpent'.
Once again we have the situation where, as more information has come to light, the Bible has been shown to be not only accurate, but accurate in minute detail. Snakes do deliberately and purposely eat and lick dust.
There is an organ in the roof of a snake's mouth called 'Jacobson's organ'. This helps the snake to smell in addition to its nose. Its darting, forked tongue samples bits of dust by picking them up on the points of the fork, which it then presents to its matching pair of sensory organs inside its mouth. Once it has 'smelt' them in this way, the tongue must be cleaned so the process can be repeated immediately.
http://www.answersingenesis.org/docs/1295.asp