Beginning in 2012, The Ag Commissioner's Office conducted an enhanced vine mealybug trapping program of 25 traps per square mile, well above the previous regimen of seven traps per square mile. By analyzing the number of males found in each of the traps, staff is able to detect new areas of infestation as well as track reductions in population.
Maps of 2013 Vine Mealybug finds in Napa County now available:
Please note: Trapping was not conducted in Carneros in 2013 because the area is considered to be widely infested as evidenced by the 2012 trap data.
Historical data also available online. View 2012 Maps
Napa County Vine Mealybug Program Components
Napa County UCCE Vine Mealybug Page
Winery Vine Mealybug Guidelines
Argentine ant management: Liquid bait program for vineyards
Mealybugs are soft, oval-bodied insects that are pink in color with a white waxy covering that extends into filaments along the margins of their bodies. Adult females lay their eggs in a white, cottony ovisac. Eggs hatch into small nymphs that are called crawlers. These young nymphs are highly mobile and may move or be carried by birds, wind, or ants to other vines. Nymphs gradually increase in size to become adult females or males. Females are the typically observed form of the mealybug, and adult males look quite different. They look like tiny wasps and are active fliers that locate the adult females by pheromone attraction. Several biological factors combine to make Vine Mealybug (VMB) a pest of great concern:
In the words of Mark Battany, UCCE Viticulture Farm Advisor in San Luis Obispo County: “The vine mealybug has the potential to become our most damaging and expensive insect pest in California vineyards.”
Ongoing Pest Management Programs Necessary
This is a special challenge in this era of reduced input and sustainable farming and requires vineyard managers to be informed, diligent, and persistent to produce high-quality fruit that is not fouled by honeydew, mold, or insects.
Growth and Vigor Reduction
VMB feeds on the plant sap of the vines and reproduces rapidly to develop high populations — the result being the reduction of vine vigor, fruit set, and growth.
Fouling of Fruit
VMB excretes large amounts of honeydew as it feeds, providing a substrate for the growth of sooty mold and reducing the quality of the harvested grapes, to the extent that fruit from untreated vines is unmarketable.
The vine mealybug, Planococcus ficus, is an exotic pest first found in California in the Coachella Valley, Riverside County in 1994. In 1998, it was detected in Kern County and Fresno County, where it was probably introduced on contaminated vineyard equipment from the Coachella Valley. For the next few years, it is believed that grapevine nurseries in the southern San Joaquin Valley shipped infested vines throughout the state before they realized the seriousness of the pest. Currently most, if not all, California grape-producing counties have infestations, including Alameda, Amador, El Dorado, Fresno, Kern, Lake, Merced, Monterey, Napa, Riverside, Sacramento, San Joaquin, San Luis Obispo, Santa Barbara, Santa Clara, Solano, Sonoma, and Tulare, and Yolo.
The threat posed by the Vine Mealybug to our vineyard and winery industry is a serious one. The insect should not be allowed to become widespread in Napa County. Low populations are less likely to spread so it is imperative to take positive steps to manage VMB . Widespread infestation means increased pest management costs in our vineyards into the indefinite future. Besides adding significantly to production costs, increases in pesticide use would be an affront to sustainability programs, and result in negative consumer reactions.