Although they prefer cabbage, the adult cabbage flea beetle (Phyllotreta albionica) will feed on your backyard tomatoes, potatoes and corn. Reaching lengths of merely one-tenth of an inch, the black adult cabbage flea beetle will chew small holes in your cabbage, potato or corn's leaves. In addition, the beetle's larvae feed on the growing plant's roots. If left untreated, the damage caused by the cabbage flea beetle is potentially deadly to the vegetables.
Till the soil after the final fall harvest to bring the cabbage flea beetle larvae to the surface, making them vulnerable to predators, such as birds, and harsh weather conditions.
Cover the newly-planted crop with a thick layer of organic mulch. According to the Washington State University Clark County Extension, the mulch makes it hard for the female cabbage flea beetle to deposit her eggs in the garden soil.
Maintain a weed-free garden, as weeds provide the growing cabbage beetle larvae with the extra nutrients required to reach adulthood.
Introduce beneficial insects to the garden. The Washington State University Clark County Extension advises that the tachinid fly and braconid wasps won't harm your crops, but will kill the cabbage flea beetles. Beneficial insect larvae is available through garden centers.
Scatter sticky traps around your garden. Commonly used to trap flies and other types of insects, these yellow traps will also attract cabbage flea beetles. Monitor the traps and dispose of them once they become full. If a trap isn't effective, move it to another spot where you notice substantial damage to leaves caused by the adult cabbage flea beetles.
Apply a thin layer of insecticidal soap to both sides of the leaves. The Washington State University Clark County Extension recommends waiting until the seedlings sprout their first leaves. Test the insecticidal soap on a small area and if no damage occurs after two days, cover both sides of the plant's leaves with a thin layer of the product. Avoid applying insecticidal soap on sunny days, as this can scald the leaves.