Aphid control on plumeria

Q: What kind of infestation do I have on my plumeria? I have sprayed it twice with a product containing sulfur & pyrethrins. The little tan insects are smaller than any aphid I’ve ever seen.

A: The tan things are indeed aphids. The white stuff nearby is their shed skins. The aphids suck sap from infested plants.

The easiest way to control them is with imidacloprid (click for sources) as contained in Bonide Systemic House Plant Granules.