Grape mealybug

Grape mealybugs appear as small, white, waxy-coated insects clustered on grape stems, leaf undersides, and around fruit bunches from midsummer through fall in warmer parts of Western Washington. The cottony wax coating is their most distinctive feature. Heavy infestations weaken vines, reduce fruit quality, and transmit plant viruses. Mealybug populations tend to build in protected microclimates and on stressed vines. You notice them moving slowly across surfaces.

Monitor vine foliage regularly starting in mid-summer for early detection. Remove heavily infested shoots where practical. A strong water spray can dislodge colonies. Apply horticultural oil or neem oil to dormant canes in late fall and early winter. Maintain vine vigor through watering and pruning. For active populations, insecticidal soap or spinosad targets crawlers.