Inside the foamy mass you will find immature spittlebugs feeding on plant tissue. Adult spittlebugs (also called froghoppers) can also be found on the plant, and are ¼ of an inch long, and green or brown.
Although not aesthetically pleasing, occasional masses of spittlebug generally do not harm established woody plants.
The best way to deal with spittlebugs is to wash them off with water, ignore them, or handpick the bugs. Pesticides are not usually effective or needed and can cause harm to pollinators that often visit these plants.