Apple Mealybug: Appearance, Territory, Damage, and Life Cycle

Latin Name: Phenacoccus Aceris

Appearance: Apple mealybug is assumed to be European in origin, although its present range is global. It was most likely brought into North America before 1910 on contaminated nursery stock.

The nymphs (or crawlers) are purplish and have a powdered wax coating on them. As they age, the coating thickens and a fringe of wax filaments forms. The adult female has no wings and resembles a nymph. It can be as long as 0.1875 (3/16) inches. It has a ring of waxy filaments that wraps around the sides of its body.

Hosts Plants: Despite its common nickname, the “apple” mealybug is far from a specialist. All deciduous fruit and nut trees (apple, cherry, pear, plum, apricot, filbert), small fruits (grape, currant, gooseberry, blueberry), and many shade trees are hosts.

Territory: Apple mealybug has been found in British Columbia, Washington, Oregon, and California in the Pacific Northwest.

Damage Insect Cause: Sucking sap will devitalize the tree to some extent, although this is probably the least of the management issues. This insect, like most sap-feeders, excretes honeydew (a high-sugar fluid excretion) that can serve as a substrate for sooty mold. The formation of honeydew, which can drip on fruit, is of more concern and will almost certainly necessitate management. Furthermore, apple mealybug can directly infest and feed on fruit, making it a direct pest of quarantine concern.

Life History and Habits: Apple mealybug has one generation per year. The apple mealybug spends the winter as a second instar nymph in a cocoon under bark scales or in bark fractures. The proboscis is used to feed by inserting it into plant tissues (bark or leaves) and sucking plant sap. They emerge from their wintering grounds extremely early in the spring, graze on twigs, progress to adulthood (male and female), and mate. In central Washington, egg-laying begins in early May.

The mealybugs appear to be fairly selective about their oviposition sites. Many of the nests are on twigs, especially in the crotches; others are in pruning scars on heavy wood, and on leaves. Early in June, eggs start to hatch, however, crawlers might not come out of the nests right once. They gradually spread out to surrounding tissues (such as leaves, particularly those close to the midribs; twigs; leaf axils; and fruit) and start eating there. Nymphs progressively mature over the summer, and in the fall, they start looking for places to spend the winter.