The most effective method is to dose it with Bayers, 2T/gallon and if they are still present a week later you can redose at 3T/gallon.

Joni from SRQ recommends Permethrin as a gentler alternative. It is derived from chrysanthemums and significantly less devastating to pollinators. She has written about it here and on her website.

I use 1 tbs Neem oil, 1 ts Dawn dish soap, 1/2 gal water mix, repeat treatment until the eggs are completely gone.
after 3-4 treatments, systemic sprinkle just make sure the buggers don't come back but I don't like to use systemic due to the fact it is such devastating to pollinators.
I've added 1 tsp fertilizer during growing season, it seems to help plant fight the battle.

Thank you! This plant never sees the outside world so no fear of pollinator death

I have a silly question: if we treat infested hoyas with a systemic insecticide, wouldn't that be in the nectar even weeks later? Making it unedible? :)

Yes, Mima, it does. Once you treat them with systemic, I would never, ever "taste" the nectar. It's sad, yes, but sometimes, it takes a serious effort to gain control over pests. They say to treat systemically about once every 6 months to stay on top of pests. This tells me that the poison stays in the plant for that long.

And BTW, this is why I have not grown compacta... so much... over the years. I do have a start of it from my sis right now, but the MOMENT I see signs of mealies on compacta, I ditch it. It's just too freakin' hard to get rid of them from this species. TOO many nooks and crannies in which they can hide... I'm sorry to say so, because it is an interesting Hoya!! So beautifully convoluted. But, ohhhh, when it gets the mealies, you might as well surrender!!!

Denise in Omaha