Could be mealy bugs or cottony aphids. There are GOY members who are very familiar with pest control on this type of plant and will most likely catch onto your question in the near future. What concerns me is that your question reads like there is a general infestation in your house and hothouse areas and it's not just one plant to be considered.

most insecticides work on the creatures nervous system and as plants don't have one then most recommended insecticides should be fine .

I use a systemic insecticide called Provado. I don't know if you can get it in America but something similar would work. It also kills other pests.

You water it on to the pot and it is taken up through the roots ... and when the pests try to drink the sap, they also drink the insecticide, and it kills them.

I also use Methylated Spirit to kill them, by dabbing it on them with a little brush.

They are a nuisance aren't they :(

Be very careful what you use on Cactus, many of them dislike insecticides and turn black if sprayed. I have lost Sedums like that, even with a little spray drift.

How about insecticidal soap? Came across a recipe for it- five tablespoons of an all natural liquid soap product in a gallon of water to be placed in a spray bottle. Has anyone tried that and found it to be effective?

Neem oil is one of those soaps and the info I have is to try it on a small section of a plant to see if it does any harm.

Provado is safe to use on cacti and succulents. I asked them before I used it, and now I have been using it for many years.
Methilated Spirit is also safe. I have used it for many years.
:o))
But always check the instructions before use.
And if you are still unsure, ask the manufacturer, like I did.

I've always used a bit of meths on a child's paint brush, it works instantly.