Who's Spitting in the Garden?
When I was a master gardener, every spring I was frequently asked what causes a mass of spittle on the stems of plants. Some people wanted to know how to get rid of it, as they considered the soap-like bubbles unsightly. Others just expressed their curiosity. I often advised gardeners to observe the plants for any damage.
Within the spittle is a tiny insect (1/8 to 1/4 inch long) related to aphids, which creates the foam to protect themselves from predators. Yes, they are feeding on the plant; nevertheless, unless they are making the plant unsightly or sickly, my advice is to relax about them. Chances are you wouldn't even know they were there except for their give-away signature of spumescent honeydew.
See if you can observe the little creatures blowing bubbles. Blowing bubbles? Yes, that is what they are doing. The frothy white mass actually comes from the honeydew the bugs secrete to cover their minute little bodies. Periodically, they stick their abdomens outside the foam, suck in some air and then retreat inside the froth and blow their soap-like bubbles.
If you rinse the spittle off gently with water, you will discover a delightful tiny green or yellow creature with dark eyes peering back at you. In my garden, these bugs are not damaging. Nevertheless, I occasionally read stories about gardens with serious infestations. Unless you have a severe invasion of the spittle, these insects are rather harmless in small numbers. When the spittle is in full bloom, you can make finding and observing the little nymphs a fun teaching moment with your children or grandchildren.
If finding them in your garden makes you froth at the mouth, and you feel you must do away with them, then hose the spittle off the plants. The predators will dive in and make a meal out of them. Otherwise, just leave them alone; by the end of May, the spittle is gone. There is no need to bring out pesticides in a garden that encourages beneficial insects.
Photographed in author's garden.
You might be interested in reading a fairy tale about these creatures—Magic Bubbles.