[NAFEX] Squirrels control using BonBon

Bassem Samaan bassem at gardener.com
Sun Oct 4 07:21:14 EDT 2009

There was an experiment done by a gardenweb member who discovered that using bon bons is not effective in controlling squirrels.
He writes:

For those interested, I am conducting another test. While not complete, the experiment if far enough along to offer some preliminary observations.
Since I'm actually trying to do research, I've decided to outline it in a somewhat detailed and formal write-up.


Squirrels have long been a major pest to fruit growers. This is especially true for backyard growers with small orchards in urban and suburban settings. The unusual combination of an abundance of food with few natural predators encourages large populations of squirrels, of which tree fruit can be a summertime food staple. To successfully grow tree fruit requires dedication. For the serious fruit grower, it can take a significant amount of time, and money. As anyone who has cared and nurtured crop has observed, there is often a significant amount of emotional capital involved as well. All to often a fruit grower nurtures a crop through the growing season, only to find squirrels have destroyed the entire crop, just before harvest. Squirrels accomplish this by:

1. simply removing the whole crop 
2. leaving some crop, but taking "bites" out of individual fruits 
3. knocking fruit off before it's ripe

In many cases experience of the squirrels' past behavior causes growers to pick their harvest before it is ripe, to prevent squirrels from stealing it. in this case, while the grower may obtain a premature harvest, fruit quality suffers.

Growers have relied on many methods to prevent fruit damage by squirrels. Each have their advantages and disadvantages. As it's not the scope of this experiment, these individual methods will not be discussed except in summary:

1. Exclusion methods- Ex. electric fencing, flashing on trunks, netting. In general, these methods have not been met with wide success. Squirrels are agile, small and deft. They are determined creatures when it comes to a favored food source, and will generally find an entry point in the barrier, or make one.

2. Offering squirrels an alternate food source during harvest- This method is generally not successful. Fruit seems to be as beloved by squirrels as it is by humans.

3. Scaring the squirrels away- Ex. plastic owls, lights, sounds, radios, etc. Poor results have been noted from these methods. Squirrels quickly become acclimated to the scare methods, rendering them wholly ineffective.

4. Shooting squirrels. Ex. shotgun, 22 cal., pellet gun. Some locales allow the discharge of firearms, some allow only pellet guns, and some allow neither. Where allowed, these methods can reduce squirrel populations, but it can be extremely time consuming.

5. Trapping- This can be done with live traps, or lethal traps such as Kania, and connibear traps. This can be successful, but can be time consuming. Traps can be expensive. Live traps are legal to use almost ubiquitously throughout the U.S. However, many states prohibit the relocation of trapped wildlife, as do wildlife specialists, so the animals must be destroyed. Kansas extension services recommends destruction by CO2 asphyxiation. Leg hold traps may also be an option, but the author no experience with this method. Leg hold traps are illegal in some states due to humane concerns.

6. Poisoning/baiting- Unfortunately, there are no poison baits labeled for squirrels that are available to homeowners. This has left homeowners to their own devices to make homemade baits. One such bait is a mixture of peanut butter and Plaster of Paris and rolled into small balls, called bon bons (hereafter called bait). This bait is currently popular with backyard fruit growers and is even used internationally. There is some debate in the fruit growing community regarding this bait. The experiment outlined below focuses on some questions outlined in that debate.


1. Attempt to determine if the bait is toxic to squirrels

2. If the bait is toxic, determine a reasonable estimate of time between bait ingestion and mortality.

3. Try to determine the mode of action of the bait. That is some believe the bait causes mortality by gastric blockage. Others surmise death is brought on by hypercalcemia (elevated blood calcium). While it is beyond the scope of this experiment to determine exact cause of death, the author should be able to observe gastric blockage. If that is case, it would rule out hypercalcemia. In the event, no gastric blockage is found, hypercalcemia would be the likely cause of death.

4. Determine if the bait causes undo pain and suffering to the animal. This may affect the decision on whether or not a grower decides to use the bait. As almost any form of death is painful to mammals, it becomes difficult to measure the relative suffering of one form of death over another. Most squirrels die in nature from sickness, starvation, or predators. As the author has never witnessed any of these occurrences, it becomes difficult to determine suffering from death of the bait, relative to more natural causes of demise they may face in nature. Added to the difficulty, is that no brain scans will be done, so evaluations must be made on external observations only. However, the author will do the best he can.


1. This experiment involves only 2 specimens. A treatment specimen (a specimen which is offered the bait) and a control specimen. Since the experiment involves such a small statistical sample, the results are not as statistically relevant as if a larger specimen sample was used.

2. There are different types of Plaster of Paris. Using a different type of Plaster of Paris may (though not likely) yield a different result.

3. Using a different ratio of Plaster of Paris to peanut butter, may yield a different result.


One squirrel was captured on Sunday, September 27th. This squirrel was the treatment specimen. Another squirrel was captured on Wednesday, September 30th, which was the control specimen. Both squirrels were kept in live traps for the experiment. Water and food dishes were placed in their cages. The squirrels did not require anesthesia to move them, or the dishes into their cages. Water was replenished twice daily. The squirrels were both male specimens of slightly smaller size. For the treatment squirrel, bait was introduced immediately and not removed until completion of the forth day of the test. For the control specimen, fresh acorns were kept in the cage at all times. Bait was mixed using exactly 1/2 cup of peanut butter and 1/2 cup of Plaster of Paris. From this mixture 6 evenly sized bon bons were fashioned. All the mix was used making the 6 bon bons. No vegetable oil was required with this mixture. A fresh 4 lb. box of Plaster of Paris was purchased for this experiment (DAP brand). According to the MSDS it contains 60%-100% Calcium Sulfate (Plaster of Paris); 10%-30% Calcium Carbonate (limestone); and 0.5%-1.5% silica.


Today is the fifth day of the experiment. So far, there has not been any observed morbidity or mortality in the treatment specimen or the control. Both the treatment specimen and control did not start eating until the second day. As was stated, bait for the treatment specimen was introduced on day 1, but not accepted until day 2. Bait was the only food available for the treatment speicimen. The treatment specimen ate the bait consistently for three days starting from the second day to the completion of the fourth day. Bait was removed the fourth day and the treatment squirrel from then on has received all the acorns it wants. Of the six bon bons made from the peanut butter and Plaster of Paris, 1/2 of the bait, or three bon bons were placed in the treatment specimen's cage at day one. From day 2 to day 4 the treatment specimen consumed two bon bons. At the end of day 4 there was enough bait left over in the treatment squirrels food dish to re-fashion one bon bon. No wastage was observed, therefore by deduction, the squirrel must have consumed two bon bons. Here is a photo of the re-fashioned bon bon. For reference is is placed next to the three bon bons I did not use. The bon bon on the right is what the treatment squirrel DIDN'T eat, out of the three bon bons placed in its cage. 

Once the bait was removed and replaced with acorns, the treatment squirrel began eating acorns normally. So far in the experiment, the treatment squirrel has not shown a decrease in appetite, whether being fed bait, or acorns. At this point, both squirrels have not shown any visible signs of pain, or lethargy.

One interesting observation is that on the beginning of day 3, the rodent droppings of the treatment squirrel turned a very light color (almost white) and became larger than normal. The droppings were very hard and broke as if they were made of Plaster of Paris. I have included some photos below.

Here is a general photo of the treatment specimen's feces taken on day 4. Notice the very light color:

Here is a close-up of the day 4 treatment specimen droppings. Notice the pellet dropping broken in half and white inside: 

Finally, here is a picture of the control rodent droppings taken on day 4. Notice the black color. Although the picture doesn't show it, these droppings are smaller than the lighter colored droppings of the treatment specimen.

The treatment specimen has been receiving acorns for over 24 hrs. and already his droppings are looking more normal (i.e. smaller and black in color).


Although it may be premature to conclude that the bait is not lethal, one may well conclude it is not acutely so. It has been 4 days since the initial consumption of bait with no mortality occurring up to this point. It should be noted, that reports indicate hypercalcemia may take up to two weeks to cause death. So if the bait is toxic, it would not exhibit quick results in this case. It is possible it does not cause hypercalcemia at all. Although rodents are very susc. to hypercalcemia, traditional rodent baits use synthetic derivatives of vitamin D to achieve this end. Rodents do not have a mechanism to properly process vitamin D. As such, vitamin D causes their system to pull calcium out of their bones, and into their blood stream. However, rodent baits use vit. D derivatives as an active ingredient, not calcium based products as an active ingredient. It may be while rodents can't process vit. D, they can process high doses of calcium without any adverse affects.

It doesn't appear that the bait causes gastric blockage. The treatment specimen ate nothing but bait for three days, and seemed to process it into "pellets" (albeit large ones) without difficulty. At this point the stool samples appear to be back to normal.

Lastly, up to this point, the bait does not appear to cause any suffering of the animal.

This concludes my write-up at this point. I will plan on adding to this report any further observations I notice.




Bass Samaan

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