First thing to do is to just spray the tree with water and get underneath the leaves.
Just doing that alone will keep the numbers down as they don’t like water.
Second, make your own Insecticidal Soap. It’s really easy. I mix 3 Tablespoons of Dish Soap and 3 Tablespoons of Olive Oil per Gallon of water. Get one of those pump up sprayers that holds over a gallon and spray away.
NO need to go out a purchase the pre mixed stuff…. Just make it.
You are getting this info from an experienced 420 Grower.
The soap has to be a real soap. Not only does it help to hold it onto tge insect but it works at dissolving the bugs outside. Dr. Bonners Castile liquid soap works well and is inexpensive. If you use it and something nasty tasting it will keep the deer and rabbits from eating your garden and easily washes off. I seem to remember that one of the nasty tasting items was chapperel which you make into a tea and mix with Dr Bonners and then spray on tge plants. I added a bunch of hot pepper extract too. Nothing like ghost pepper or even hanenaro pepper extract boil with other nasty ingredients when you make the tea so the oils get in. As a safety note don’t use anything poisonous