They eat this and the cement expands in their stomach and intestines which kills them. The critter's body provides the water or maybe they drink from a puddle. But the dry cement plus water does them in
I am pretty enthused about this deterrent. I am not sure what was attacking/eating from my Kent mango tree but there have been no attacks for three days. The previous bon-bons were devoured. In photos are the new bon-bons. I know this is a short time to really test this but...
This deterrent might be a problem for dogs you have...Mix the cement and peanut butter in a 1:1 ratio then add what you need to make it more solid or more pliable. Not dry. You want to roll it into a bon-bon ball. A candy for them. I sprinkled these with sugar too but not the previous ones. You can top these critter bon-bons with pure peanut butter to better get their sense of smell homing in on it. Maybe put a half eaten mango near the bon-bon dish.
You have to give the bon-bon dish a roof so they don't get rained on. I used an old plastic election sign. Better to paint them white for your neighbors. So they don't ask questions. Make them as inconspicuous as possible.
It seems to me you can extend the peanut butter with a bit of vegetable oil. Add bacon fat? Add some raw or cooked bacon? add salt? Experiment with what you think they (possums, rats) want to eat but the basics are simple-
1)Portland cement
2)Peanut butter
3)no water!
I used from a bag of 100% Portland cement. Not one of those sakrete pre-mixes that have gravel mixed in. But you can take one of those pre-mixes and sift the gravel out so you have 100% cement to work with. So you get the ratios right. You could even use a large kitchen strainer outside to sift out the gravel (aka aggregate)