Grape Mealybug, Pseudococcus maritimus (Ehrhorn) (Homoptera: Pseudococcidae)

The grape mealybug is a common pest of grapes. The adult mealybug is 1/8 inch long and cottony white. Although the mealybug does not ordinarily occur in numbers great enough to cause serious injury, individuals can always be found in vineyards. Mealybugs remove sap from the plant and deposit honeydew on the leaves and fruit, which act as a medium for sooty mold development.

The mealybug overwinters as an immature form (first instar) within a cottony mass produced by the female. During April and May, the young mealybugs become active, sucking sap from the new shoots. Development is completed by late June and the adult female lays eggs within a cottony structure, an ovisac. Eggs hatch in a few days, and the small mealybugs start to feed, many finding their way into the clusters and removing sap from stems and pedicels of the clusters. By late August, the mealybugs reach maturity and lay eggs, which give rise to the overwintering population of mealybugs. Eggs that do not hatch before the onset of cold weather in the fall do not survive winter.

Mealybugs have several natural enemies. A parasitic wasp and a predaceous insect attack the eggs. All stages of the mealybug are prey for ladybugs.

Current pesticide recommendations may be found HERE

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