Look for ants on the plant. Ants do not feed on kadipatta leaves, but their presence indicates that the scale insects that do are likely there, usually feeding on the bottoms of the leaves.
Shower the kadipatta plant with lukewarm water. Drench the underside of the leaves. Kadipatta plants are most vulnerable in cold, dry weather -- conditions that most often occur in North America during the winter season.
Use horticultural oils specifically designed to control scale insects. Horticultural oils are sold at farm supply stores or farm co-ops. Dilute the oil according to the manufacturer's directions before use. Older plants can become vulnerable to scale insects even when they are not in cold, dry weather. Horticultural oils are generally effective in killing the pests.
Try capsicum extract, taken from hot peppers. Mix it with a dash of dish soap and add it to a spray bottle filled with water for a natural spray that will rid older plants of scale insects.