Jack Russell Terrier destroying things

We have gotten to the point where we can leave our Jack Russell in our home to roam freely when gone for up to 6 to 8 hours, with no damage. Recently my husband went to an out of state conference. While I was a work we had a friend come over to take our Jack Russell out a couple of times during the day. First day was okay and then on the days following I would come home to find that he tore open the bed comforter and pulled out the stuffing. This happened for two days straight. Now we are afraid to leave him out for more than a couple of hours. What would cause this?