Natural methods to control pests on Plumeria include using horticultural oils, insecticidal soaps, neem oil, or introducing beneficial insects like ladybugs, lacewings, and parasitic wasps. Maintain a diverse garden with various plants to attract beneficial insects that prey on pests. Regularly inspect the plant for signs of infestation, and remove pests manually if possible. Use natural repellents like garlic or chili spray to deter pests.