Answer: The insects feeding on your grapes are most likely yellow jacket wasps. The best control is to pick the ripe fruit every few days, harvesting in the late afternoon or early evening when the yellow jackets are less active, says Phil Nixon, entomologistat the University of Illinois, Urbana. Wasps, hornets and bees are attracted to diseased, damaged or overripe grapes, so removing any such fruit will lessen the problem. However, yellow jackets will feed on good grapes, too, explains Nixon. Sprays are only marginally effective because wasps can migrate. You'll just have to beat them to the bunch.
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