One fact of gardening life that many gardeners hate to deal with is bugs and organisms feeding off the very plants they are trying to grow. This is especially problematic when it involves fruits and vegetables that the gardener may be counting on as a main food source. One of these invaders is the whitefly, and it loves to drink the juices from tomato leaves. If you spot these small insects, you'll want to get rid of them right away, before they can feed or spread plant diseases.
Strip any severely infected leaves from the plant with pruners or a sharp knife, and discard them in a plastic grocery bag. You don't want to compost these leaves because you'll be adding the whiteflies to the pile.
Remove as many whiteflies by hand as you can by running your gloved finger along the underside of the leaves. Squish the whiteflies between your fingers or wipe them along the ground to crush them.
Spray the hose at the undersides of the tomato leaves on a hot day to knock the whiteflies off. This won't release the eggs, but the adult flies should come off under the pressure of the water.
Use an insecticide following manufacturer's instructions to kill off the whiteflies and their eggs. Typically a spray works better than a powder and should be applied to the undersides of the leaves.
Set or hang a yellow sticky trap on or near your tomatoes to keep further infestations down. Like fly tape, the whiteflies should stick to the inside of the card when they land on it, thus preventing them from making it to your tomatoes.