We have cut some hickory and it does stain from the stickers if you use anything but cottonwood. We have some more logs to cut soon and they may not be any good as I see worm holes in the bark. Hickory will turn different colors depending on the speed of drying. So, with stickers that are wet, you will see stain. If the wood between the stickers dries faster than the wood under the stickers, you will see stain.
Insect damage is always a risk when they are around.
Gene Wengert, forum technical expert Powder post beetles love hickory and ash. Before I would sticker the green hickory, I d treat the lumber with an approved insecticide for powder beetle control. Stack your lumber properly outside with protection to get quicker drying from the outside winds. Don't forget to seal the ends of your lumber. The powderpost beetle in ash and hickory is not the same one that gets into dry lumber.