That looks like a whitefly.
@Rainbowgardener, I didn't know there were *wooly* whiteflies as well as wooly aphids.
(those photos are scary severe infestations
I didn't know about banana peel as repellant until pepperhead mentioned it a while back. I still don't know if it's the smell or if the added potassium helps to strengthen the plants, making them less attractive and increase the plant's immunity..... but once infestation is evident, you do need to physically remove them somehow -- alcohol that rainbow mentioned, insecticidal soap, etc. (I suspect the fluff protects them from the milder solutions...)
Sticky traps are usually recommended to catch the flying winged buggers, especially in the south where whiteflies can spread virus -- yellowtop? curly top? -- can't remember the name of the disease for sure.