Woodpeckers eat happily on the insects found in tree trunks.  When there is insufficient food available in those trees, they enjoy eating from feeders made to accomodate them.  Suet feeders and peanut feeders are both appreciated by the woodpecker family.  Many suet feeders have special tail-props to assist the woodpeckers, as the woodpeckers body is more rigid and doesn't bend easily. 

Special elongated feeders, known as Woodpecker Feeders, provide another alternative.  These feeders can be filled with a seed mix, usually called a Woodpecker Mix, that contains all the favorites of the woodpecker family.  There are no perches or platforms, but seed ports above a long brace area from which the woodpecker will rest and eat.  It's uniquely designed to recreate the position of eating on a tree trunk.