Answer: Your problem is grape phylloxera, a small, aphidlike insect that feeds on the roots and leaves of grape varieties. This pest almost destroyed the grape crop in France in the 1800s, says Mary Howell Martens, assistant grape breeding specialist at the New York State Agricultural Experiment Station in Geneva. Phylloxera adults feed mostly on grape roots, but in midsummer the insects emerge from the soil and lay eggs on leaves. The eggs hatch and larvae feed on the leaves, forming galls. The larvae emergehe adds. In that case a single spray of carbaryl (Sevin) at grape bloom time should do the trick.
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