Something eating plumaria tops
My guess is that it's cutworm larvae or Frangipani caterpillar. Try an application of bT (Bacillus thuringiensis). It only works on caterpillars or foliar feeders. You could also add food grade diatomaceous earth into your soil to help with snails and slugs.
Here's a great pest chart from the plumeria society and an article from plumeria today!