Bugs. Just wipe them off with your fingers. Are they only on that one leaf?

White flies

Mealy bugs. Small infestations can be controlled by removing them manually with a q-tip or hosing them off. Insecticidal soap spray is said to help effectively too. Careful with neem products as some plumeria don't seem to like that as the oil clogs the stomata, causing leaf drop.

I get a wet paper towel and wipe it off and then I use Bayer 3-1 because it's the best I've found over the years. Once I spray the plants once with Bayer 3-1 I don't have problems at all for the rest of that summer....Mayne spray twice about a month apart and you really shouldn't have any problems. You can get Bayer 3-1 from Walmart, Lowes or Home Depot. It's about $15 per bottle but one bottle goes a long way.

All, many thanks. Dave and David, hit them with a Q-tip and Kapow...the bugs leap off the leaves in nothing flat. Hendo, thanks also...I think I'll hit the leaves with some Beyer after the Q-trip drill. Thank you all.

It's the Flatid Planthopper. And really all you need to do is wipe them off, like I mentioned. Most will jump off.