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Summary of Possum Repellent Study

A recent study by Deakin University in Melbourne set out to test the repellency of fourteen products most of which are commonly used to deter possums. The following is a summary of this study and does not represent the Department of Sustainability and Environment’s view or endorsement of any of the products listed.

Products tested included:

All of these products are readily available either at the supermarket or at a plant nursery with the exception of Bitrex. Bitrex is a bittering agent commonly added to make certain products unpalatable and is an ingredient in some proprietary repellent products, such as D-Ter®.

Products were organised in categories according to their supposed method of repellency, either by taste (gustatory repellents) or odour (olfactory repellents). Different tests were devised for each category. Two of the products were tested in both categories because they could conceivably repel by both taste and odour (garlic spray and D-Ter®).

Gustatory repellents were tested on piles of apple pieces laid out in a grid pattern, with untreated apple and three different repellent treatments tested in each trial of two hours during which wild possums had free access to the food. The behaviour of the possums and the amount of food in each treatment remaining at the end of the trial period were recorded. The results showed that when possums were hungry, none of the repellents prevented them from eating all the apple provided. The products tested in this series of trials included: Tabasco sauce®, Hot English mustard, Indonesian fish sauce, Bitrex, Garlic spray and D-Ter®.

Olfactory repellents were tested by placing treated and untreated chopped apple in a cage suspended above the ground. A counter recorded the number of times a possum attempted to gain access to the contents of the cage. A large number of attempts to get the untreated apple, compared with few attempts to get at the treated apple would be taken as an indication of successful repellency.

The results suggested that five of the tested compounds may show some degree of repellency. These were: White King®, Keep Off®, Camphor, Naphthalene and Scat®. The other products tested in the olfactory trials were: D-Ter®, Stay Off®, Blood and Bone, Garlic and Quassia chips.

It should be noted that these trials were undertaken on one population of possums at one site. The results do not necessarily indicate that similar responses will be displayed by possums elsewhere, or that other kinds of tests would yield similar results.

Reference

Cooney, Janine 1998. An evaluation of commonly used deterrents for urban Common Brushtail Possums Trichosurus vulpecula (Kerr, 1792). BSc (Hons) Thesis, School of Ecology and Environment, Deakin University.

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