This mid-summer generation reproduces, creating a second generation that reaches maturity late in the season. Vines can tolerate the removal of sap by mealybugs, but their excrement is the main cause of damage. The blackening of grapes shown in the photograph below is caused by sooty mold fungus that develops on the honeydew secretion. Mealybugs are naturally kept under control by lacewings, ladybirds, pirate bugs, and spiders. Maintaining a pest management program that does not destroy your bio-control agents is the easiest way to avoid mealybug problems.
Chemical control works best when sprays are aimed at the mobile crawler stage.
When mealybugs are in the egg sac, or settle and are covered with wax, it is harder for insecticides to reach them. Addition of oil to a dormant spray has been recommended in California to increase penetration of insecticides into cracks. Timing will be critical to effectiveness of any management plan. We currently do not have much experience with mealybugs or with their management in Michigan vineyards. We hope to learn more about this pest during 2001.