Spot Them Early
Usually vegetable gardeners are the ones concerned about spotting flea beetles early. White sticky traps, available commercially, provide early warning of flea beetle infestation.
Trap Crop Trick -Bok Choy and other varieties of Chinese cabbage as well as radishes can be used as trap crops to spot early infestations of flea beetles. Locate them in or within 10 to 15 feet of the crop threatened by the beetles.
Prevent By Barriers
When a plant is in seedling stage, a fine cheesecloth or fleece barrier is effective in keeping flea beetles away.These materials prevent the flea beetles from getting to the plant. When the plants have grown some and become well established, remove the cover.
Older plants that get some flea beetle attention can be protected by dusting them with powdered lime or diatomaceous earth. Sprinkle diatomaceous earth around the base of vulnerable plants to keep flea beetles away, or dust the whole plant with the earth. These materials usually must be replaced after a rain, so are not very practical for a large number of plants at the same time.