Ornamental Plants

Mealybugs

Mealybugs have oval-shaped, flattened bodies that are covered with white powdery material. Some species have elongate waxy filaments extending from the margins of their bodies. Like soft scales, aphids, and whiteflies, mealybugs have piercing-sucking mouthparts and produce honeydew, which supports the growth of sooty mold fungi. Female mealybugs remain wingless throughout their life, eventually producing cottony egg sacs containing hundreds of eggs. Eggs hatch into small nymphs that somewhat resemble adult females, but may differ in color. Male mealybugs are winged, but are rarely seen. Mealybugs can build to high populations and cause damage by removing plant sap, producing honeydew and sooty mold, and causing distorted plant growth. Mealybugs are more common in greenhouses and indoor settings, but outbreaks occasionally occur on outdoor plants. Gardeners should be aware that the larvae of some species of beneficial lady beetles superficially resemble mealybugs.

Control Mealybugs: For fast-acting control of mealybug infestations, spray with a product that contains acetamiprid (Ortho Flower, Fruit, and Vegetable Insect Killer); this is one of the more effective foliar spray treatments for mealybugs. Sprays of horticultural oil or neem oil will also control mealybugs, but only with thorough spray coverage. Soil-applied systemic treatments with products that contain dinotefuran (Zylam or Safari) are slower-acting but will provide longer-lasting control.

See Insect Pests of ornamental plants in the home landscape, page 6 and pages 39-41 for more information on mealybugs.