In Phoenix, Az we have an acute roof rat problem. One evening while swimming I saw an army of roof rats running across our telephone lines to the neighbors trees. We have a large ficus tree that bisects the lines so that the rats run through our trees and continue to our neighbors. Watching this I though lets use the rats weakness to our advantage. I found a small pale, crushed the Tom Cat brand of bate box rate poison , these green cubes that are placed in bate boxes, I crushed around 11 cubes and mixed with chunky peanut butter.. Then smeered the branches with peanut butter and place the pale in the tree. The next day most of what I placed was gone. I repeated this everyday .. two weeks later I found the dried up remains of all sizes of the critters. I still continue to bait the tree with great results.