Insecticidal soap is effective on the crawlers or young scales. It is less effective against the adult scales. Adult females will lay eggs under their body. This causes them to raise up off the plant. Use your magnifying glass to time your insecticidal soap application so it coincides with the time when the crawlers are most active and present in the highest numbers.
Insecticidal soap kills only by direct contact with the insect.
Be sure to apply it to all surfaces of the plant where scales or mealybugs are found. Before using an insecticidal soap, check the label to see if your plant is listed. You may have to test a small area on your plant for phytotoxicity. It may take seven to 10 days for phytotoxicity to show up. If your plant shows sensitivity, rinse the soap off your Ficus once the insects are killed.