The three most important mealybugs (below) in the North Coast are vine mealybug (VMB), grape mealybug (GMB), and obscure mealybug (OMB). Gill's and long-tailed mealybug are present in other regions, but not prevalent in the north coast. Mealybugs can be found anywhere on the vine (trunks, cordons, leaves, etc.). They are phloem-feeders, and excrete honeydew. Excessive honeydew can lead to the growth of sooty mold that can soil leaves and clusters. All vineyard mealybugs transmit grapevine leafroll-associated viruses (GLRaV). Male mealybugs do NOT transmit GLRaV because they do not feed in the adult stage; as nymphs they are vectors.

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More information: UCIPM: Vine mealybug, UCIPM: Mealybug identification, UCCE Napa County, UCCE Sonoma County

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Information adapted from materials made by UCIPM, UCCE Napa, UCCE Sonoma, and Bettiga et al. 2013. Grape Pest Management. Third edition. University of California, Agriculture and Natural Resources, Richmond, CA, USA.