Idaho Code § 34-912
When any vacancy occurs after the printing of the ballots and is filled as provided by law, the county clerk shall thereupon have printed a sufficient number of stickers containing the name of the candidate designated to fill the vacancy and shall deliver them to the judges of elections of the precincts interested therein.
The distributing clerk shall affix such stickers on the ballot before it is given to the elector. The sticker shall be placed over the name of the previous candidate. If the vacancy occurs after the deadline for filling the same, the distributing clerk shall cross the name of such candidate off the ballot and no votes shall be cast for the candidate. The county clerk shall notify the precincts of this authorization as soon as a vacancy occurs.
Idaho Code § 34-912