Which is the best Yates product to kill caterpillars on my Eumundi Quandong trees (image attached)

Wow!  That poor little tree has been munched!

Try 'Yates Nature's Way Citrus & Ornamental Spray (Pyrethrum Plus Oil Pest Spray)'. Controls a wide variety on insects pests on many edibles and ornamentals.  

Click here for more info on this product:

https://www.yates.com.au/product/garden-pest-control/yates-natures-way-citrus-ornamental-spray 

Unfortunately, Nature's Way Citrus & Ornamental Spray is not available in a concentrate.  If you have a lot more plants to treat for caterpillars, try ‘Yates Nature's Way Caterpillar Killer - Dipel’. This product controls a wide range of leaf eating caterpillars and is safe to beneficial insects, birds and animals. Approved for use in organic gardening.

Click here for more info on this product: https://www.yates.com.au/product/garden-pest-control/yates-natures-way-caterpillar-killer-dipel