Will neem oil kill Japanese beetles on roses if not what can
Certified GKH Gardening Expert
The Neem Oil will get the adult Japanese beetles and you need to kill them to stop the cycle of larvae to adult. I would also recommend treating all of the non-edible plants, shrubs and rosebushes with Bayer Tree and Shrub granules. Apply the granules per the label instructions and also spray with the neem oil. Make sure your neem oil is a fresh batch. Neem oil that has been stored in a hot garden shed for over a year will have started to break down and lose its effectiveness. Storing it in a cool, dark place is best for it to not break down so fast. There is also a natural method to get after them called Milky Spore but it can take a long while to get developed well enough to really get after them. Another spray that gets after the adults and the larvae is Bayer Advanced Complete Insect killer.