All citrus are prone to many diseases and insects. Your damage looks like mites, which won't harm the fruit, but will weaken the tree in time. Spraying with insecticidal soap will take care of the mites, but won't prevent citrus greening virus that has spread from Fla. to Ca. The best you can do is give it good cultural care...feeding/watering, and hope for the best. Mealy bugs and Scale are other insects that can weaken your tree, but the soap will take care of them also.
