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University of California Cooperative Extension Obscure Mealybug
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| Distribution
& Damage Monitoring Return to main menu |
The obscure mealybug is a close relative of the grape mealybug, and it is often difficult to distinguish between the two. |
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The obscure mealybug can be found in the United States, Europe, New Zealand, and Australia; however, its origin is not known. It has a narrower tolerance to temperatures than the grape mealybug and, as a result, is found primarily in the cooler regions of the Central Coast. The obscure mealybug has a larger host range than the grape mealybug and, for this reason, is an important pest on agricultural crops in glasshouses and indoor ornamentals. In vineyards, the obscure mealybug has two to three generations per year, depending on temperature. In mild climates, there is no diapause, which results in multiple overlapping generations with all life stages present on the vine. Like the grape mealybug, the obscure mealybug overwinters under the bark of the trunk, spurs, and canes. In spring, this mealybug begins to feed on leaves and continues through veraison. Still, the greatest portion of the population is hidden under bark or in tight grape clusters. At harvest, populations may increase dramatically, perhaps due to an increase in females' reproductive potential. However, the causes of this sudden growth in population are still being researched, and some populations do not seem to experience it al all. With a good food source and mild temperatures, an obscure mealybug female can lay up to 500 eggs in the cottony ovisac. (Return to top) |
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| Monitoring
To find new infestations, look for overwintering nymphs under loose bark on spurs or on young leaves and shoots (in the first 2 to 4 inches [5 to 10 cm] of growth). Near harvest, cut open tight clusters that are close to the trunk and look for mealybugs. Populations of obscure mealybug on the Central Coast are closely associated with the Argentine ant, which tends the mealybug for its honeydew. Therefore, a good search method for obscure mealybug (and other mealybugs) is to look for ants on the vine. The obscure mealybug can also be found on the roots of common vineyard weeds. (Return to top) |
