clipped from: www.gardeningknowhow.com Other than looking unsightly, spittle bugs do very little damage to a plant. They do suck some of the sap from the plant, but rarely enough to harm the plant. The plant foam serves mostly to hide the adult and immature spittle bugs.
If you are reading this, you probably asked yourself, “what bug leaves white foam on plants?” The answer is a spittle bug.
The tell tale sign of spittle bugs is plant foam. This plant foam will normally appear in the where the leaf attaches to the stem or where two branches meet. It will look like white foam, a pile of bubbles or a big gob of spit.