Check out your Co-op if you have one near you, they can help. If not, go to Wally World and start reading labels. Lowes or Home Depot also will have insecticides. You will have to get the spray on the trees when they are in bloom, that's the time the insects get into the blossom. Note the chemical contents, lots of brand names, just different, or the same chemicals. Also note the % of the chemicals. The higher the percentage, the more you may be able to dilute. Some of the more concentrated types require a USDA users permit, which you have to attend a class in hazardous chemicals. The class is about 3-4 hours long and gives you a lot of info. This is how the farmers get certain chemicals that the ordinary gardeners can't use.

Russ