|Spittlebug Froth photo UC Davis|
While weeding near my bee balm (Monarda), I saw several patches of a frothy white substance on the leaves. Upon further study, I discovered that I have a small infestation of the spittlebug. Aptly named, the white froth is what the immature spittlebug or nymphs surround themselves with as they feed on plant tissue. Adult spittlebugs are inconspicuous, often greenish or brownish insects, about 0.25 inch long.
While spittlebugs suck plant juices and can distort plant tissue and slow plant growth, they do not seriously harm plants. As they don’t cause significant damage, just wash them off with water if their appearance bothers you. Otherwise, enjoy yet another fascinating bug in action!
Here’s more information: http://www.ipm.ucdavis.edu/PMG/GARDEN/VEGES/PESTS/spittlebugs.html