Quassia Chips
Picrasma excelsa
Quassia chips come from the white bark of Picrasma excelsa a tree that is indigenous to Jamaica and many other islands of the West Indies. The tall elegant trees are not troubled by insects or pests as the entire tree in particular the timber, contains quassin an astringent resin which is a bitter and very effective insecticide.,
Quassia is used for debilitated digestion and loss of appetite, as in convalescence. It is also used for Anorexia nervosa, malaria, nematode worms and threadworms. Externally it can be used for Lice infestations.
Quassia Chips contain insecticidal properties against flies, red spider mite, aphid and woolly aphid. It is also great to repel possums.
Using Quassia Chips as a possum deterrent

To repel possums in the roof the chips can be spread around the area where they are entering the roof as well as throughout the roof cavity. Homemade Quassia spray is easily made and can also be sprayed around the roof cavity and entry points.
To repel possums in the garden
For ornamental plants you can spray on the leaves, stems and trunk of the plants, you can also do this on fruit trees avoiding any soft skinned fruit that is ready to be picked.
If you are protecting your edible herbs and vegetables from being the eaten it is best to spray to saturate the ground around the plants, if the quassia is sprayed on the foliage of your herbs and vegetables they will not only taste bitter to the possums but also to you!
Apply quassia spray for 5 days in a row. This should be long enough for the possum to realize that this is not the tasty treat that he thought it was. Re apply the quassia spray after rain or watering. If the possum comes back for more repeat the spray for another 5 days.
To make a spray to repel possums and insects
Add 25g quassia chips to 500ml water in a saucepan bring to the boil, turn heat down, cover with a lid and simmer for 30 minutes, strain and add 25ml liquid soap. This is then diluted 1part to 3 parts of water before use. Put in a spray bottle to apply to affected area.
Bucket method
You can also make a spray by soaking the chips in a bucket of tap water, use around 200g of quassia chips to a 9-10 litre bucket of water let them soak for 24 hours before straining off the bitter liquid. This can then be sprayed on the affected area.
Adding 5g of pure soap flakes per litre of spray is an effective wetting agent for the above spray.
Don't spray it on food crops less than a week before you consume it
Parts Used
Stem wood
Actions
Bitter tonic, sialagogue, anthelmintic
Contraindications
Excess causes gastric irritation and vomiting.