luis_pr said:Hydrangeas are normally not bothered much by cicadas and when they are, the stems are affected when they lay eggs.
https://ask2.extension.org/kb/....
I would try to catch the pest in action although it is possible too that they have already "left". Look under all the leaves, in the stems/branches and in the soil and under rocks. Some of these pests damage the leaves only at night so have a flashlight handy. At this point, the problem seems cosmetic, not major.