Those are actually called white flies, and they can take over when a plant is stressed and/or doesn't have enough air circulation. Wash them off, and the sticky stuff they might leave, with a hose. Make sure the plants nearby are at least 2 feet away. Then work on getting your plant strong and healthy.
Be sure to water regularly, let it drip over a couple-hour period rather than just stand there for a minute with a hose.
Is this in a pot or in the ground? If it's in a pot you might need a saucer to collect the water, then the main pot can suck that water back up over the next couple of hours. Water will find it's way through a pot, run out the bottom, and not even saturate all the soil.
If you can add 2 inches of compost, even bagged potting soil that is high in compost, but not wood products, on top of the soil out to where the branches reach, then cover that with crushed leaves or mowed grass.
All these things will improve your soil, which will improve your plant's immune system, and it can fight off most critters.
Love your soil.....feed your worms...
(Used to be Sweetpea, contributing here since 2002)