Pink hibiscus mealybug, scientifically known as Maconellicoccus hirsutus, is a destructive pest that damages not only hibiscus but citrus trees and other tropical fruits and ornamental plants.
While no insecticides have been found to be effective in controlling pink mealybugs, they have natural predators that are easily mobile--the most common of which are lady beetles, more commonly called lady bugs. Biological controls can help to manage and reduce mealybug populations to levels where damage is minimized.
While not always deadly to hibiscus, the mealybug activity can cause shriveling and misshapen leaves and buds and stunted branch tip growth. Like aphids, they also release honeydew, which attracts sooty mold spores, adding to the degraded appearance of the plant.
Acquire a supply of lady beetles or their larvae (known scientifically as Cryptolaemus montrouzieri), which will hunt and consume the pink mealy bugs. Horticultural supply companies and nurseries can advise on the amount of lady beetles needed for the number of hibiscus plants you have and the degree of infestation you are facing. They can be ordered online or by mail.
Release the lady beetles into the hibiscus plant in the late spring or early summer (as mealybug populations will begin to swell) or whenever you notice the problem.
Set the open box or container of lady beetles in the shaded crotch of the hibiscus tree or shrub and allow the beetles to climb out and disperse on their own without any threat of damage to them caused from shaking them out over the plant.
Repeat the introduction of lady beetles each year or as needed to keep the population of mealybugs in check.