Camphor. Please note that this is POISONOUS and should be used very carefully. Dick Missett tells us. \"A friend of mine with an sob had a problem with mice every year. I told him that using Camphor was discussed here on the GMC net. he ordered some from the local pharmacy and the mouse problem went away. That was two years ago. I have also heard that using cedar blocks ( available at Wally World & K-Mart) is effective\"