Secondary Symptoms - They will feed on the roots; bark; foliage; and fruit. The citrus mealy bug injects toxic saliva while extracting plant sap; resulting in defoliation; fruit discoloration; fruit splitting; and fruit drop.Mealy bugs usually gather in large numbers; causing premature leaf drop and twig dieback when they feed. Like psyllids; they secrete honeydew which attracts black sooty mold.