Apple Mealybug

Despite the common name of “apple” mealybug, this insect is by no means a specialist. The host range is very broad, including all deciduous fruit and nut trees (apple, cherry, pear, plum, apricot, filbert), small fruits (grape, currant, gooseberry, blueberry) many shade trees (maple, oak, birch, willow, ash, linden, elm, mountain ash) and various ornamentals (cotoneaster, hawthorn, quince, spirea). The alternative common name, the polyphagous tree mealybug, is more indicative of this broad host range.

Eggs: The eggs are oval, ca. 0.3 mm long, and lemon yellow in color. Eggs are laid in ovisacs or nests consisting of dense cottony material covering a mass of separate eggs. The nests are 4-9 mm long, 1-3 mm wide, and can be found on the trunk, twigs, or leaves of apple. The ovisacs contain up to several hundred eggs. Apple mealybug nests can be distinguished from grape mealybug nests by their appearance: the grape mealybug is a loose, cottony mass, whereas the apple mealybugs nest is a well-defined cottony cylinder.

Nymphs: The first instar nymph is lemon yellow like the egg, and about the same size (0.3-0.4 mm), but with bright red eyes. Nymphs remain in the nest for a while, and gradually disperse to nearby plant tissues. Soon after they begin feeding, they develop the mealycoating (a granular white waxy covering) waxy filaments at the caudal end that is typical of mealybugs. This is well developed in later instars.

Adults: The adult female is 3-4 mm long, with a sage green body color visible through the white waxy coating. The tails on the caudal end of the mealybug are shorter than those of grape mealybug, and the body color (green vs pale purple) distinguishes it from grape mealybug, the most common mealybug pest in Washington tree fruits. The male is a typical of the Coccoidea, winged and relatively delicate.