Fill a jar 1/2 full of water. Pour in approximately 1 tbsp. of dish soap. Stir the water with a spoon to mix the soap with the water.
Take the jar of soapy water, a pair of garden gloves and a flashlight outside to your grapes at dusk. Dusk is when most bugs are present, according to "Gardening for Dummies."
Don a pair of garden gloves and turn on the flashlight. Look for bugs on the grapes. Pick up bugs you find and place them in the jar of soapy water. The soap will coat the wings of the insects and prevent them flying out of the jar.
Sprinkle pyrethrum powder on the grapes and vines every three to five days, or as directed by the label. Pyrethrum powder is an insecticide that prevents insects from returning to the grapes.