Foam like eggs on weigela Florida
The foam on the stem is produced by a spittle bug nymph (youngster). As adults, they are called froghoppers.
Spittlebugs are pests which seldom cause serious damage to plants. They feed while underneath the foam. Their feeding activities may cause the flower stem of lavender to topple.
To get rid of the foam, wipe it off with tissue, or use a forceful water spray from the hose.
Enjoy your weigela. they are stunning when in full bloom.