Something grabbed my mind today while stacking wood with my boys. I lifted a pallet that had cross slats on both top and bottom and half the bottom slats were completely eaten away. about 1 year sitting on the ground. The cross slats were soft wood...probably pine. the 3 support rails were oak and seemed completely untouched by the bugs. Earlier in the year I noticed this same phenomenon with several other pallets that were constructed this way. In the woods I have seen fallen oak trees that area all but completely eaten away by bugs within 2 years. Assuming that the oak rails on the palets are not treated, what would make them rot resistant and the fresh fallen oak trees a bug buffet?